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MINING  AND  MINE  VENTILATION 

A  PRACTICAL  HANDBOOK 

ON 

THE  PHYSICS  AKD  CHEMISTRY  OF 
AND  MINE  VENTILATION 


FOR  VOCATIONAL  SCHOOLS,  AND  FOR  THOSE 

QUALIFYING  FOR  MINE  FOREMAN  AND 

MINE  INSPECTOR  CERTIFICATES 


BY 

JOSEPH     J.    WALSH 

Mine  Inspector,  Wilkes-Barre,  Pa. 
ILLUSTRATED 


NEW  YORK 

D.  VAN  NOSTKAND  COMPANY 

25  PARK  PLACE 

1915 


77/30  / 


Copyright,  1915 

BY 

JOSEPH  J.  WALSH 


THE  SCIENTIFIC  PRESS 

ROBERT  DRUMMOND  AND  COMPANY 

BROOKLYN.  N.  Y. 


PREFACE 


IN  adding  to  the  number  of  text-books  on  Mine  Venti- 
lation the  author  aims  to  provide  new  material  and  to 
dwell  more  fully  on  the  fundamental  theories  and  laws  of 
ventilation,  and  to  furnish,  if  possible,  to  the  student  a 
more  suggestive  method  of  study  in  a  more  graphic  form. 

While  ventilation  experts  practically  agree  upon  the 
essential  theorems  in  ventilation,  it  is  believed,  however, 
that  the  subject  may  yet  hold  a  new  attractiveness  and  be 
more  readily  mastered  if  a  few  important  principles,  which 
are  now  generally  misunderstood  by  the  student,  are  mag- 
nified. 

The  method  of  determining  the  size  of  fan,  etc.,  to  ven- 
tilate a  mine  under  given  conditions,  together  with  certain 
facts  pertaining  to  the  water  gauge,  and  the  chapter  on 
Mine  Fires  are  entirely  new  features. 

The  author  wishes  to  express  his  gratitude  to  the 
Robinson  Ventilating  Co.  of  Pittsburgh,  Pa.;  The  American 
Blower  Company,  and  their  manager,  Thomas  W.  Fitch, 
Jr.,  Detroit,  Mich.;  The  Jeffrey  Manufacturing  Co., 
Columbus,  Ohio;  The  Colliery  Engineer,  Scranton,  Pa.; 
M.  B.  King,  Expert  Assistant  in  Industrial  Education, 
Harrisburg,  Pa.;  and  The  Taylor  Instrument  Co.,  Roches- 
ter, N.  Y.,  for  many  illustrations,  tables  and  other^infor- 
mation  used  in  this  book. 

J.  J.  W. 

WILKES-BARRE,  PA., 

June  1,  1915. 

iii 

345970 


CONTENTS 


PAGE 


CHAPTER  I 

MATTER 
Matter  and  its  Properties.    Hooke's  Law 

CHAPTER  II 
MOTION,  VELOCITY  AND  FORCE 

Motion.  Newton's  Laws  of  Motion.  Velocity.  Force.  Parallel- 
ogram of  Forces 

CHAPTER  III 
GRAVITATION 

Newton's  Law  of  Gravitation.     Weight.     Effect  of  a  Constant 

Force.     Formulas  for  Falling  Bodies 12 

CHAPTER  IV 

LIQUIDS  AND  LIQUID  PRESSURE 

Specific  Gravity,  or  Relative  Density.  How  to  Find  the  Specific 
Gravity  of  Bodies  Lighter  than  Water,  of  Liquids.  Table  of 
Densities 

CHAPTER  V 

HEAT 

Thermometer.     Conversion  of  Thermometer  Readings.     Table  of 

Melting-points.     Table  of  Temperatures 27 

v 


vi  CONTENTS 

CHAPTER  VI 

GASES 

PAGE 

The  Atmosphere.  Composition  of  the  Atmosphere.  Atoms 
and  Molecules.  Elements.  Table  of  Elements.  Density. 
Specific  Gravity.  Table  of  Gases 32 


CHAPTER  VII 

GASES 

Chemical  Compounds.  Mechanical  Mixtures.  Chemical  Sym- 
bols. Atomic  weight.  Molecular  Weight.  Chemical 
Equations.  Hygrometer  and  Its  Use.  Table  of  Water 
Vapor  Contained  in  Saturated  Air.  Absolute  Humidity. 
Relative  Humidity.  Dew  Point.  How  to  Find  Relative 
Humidity  and  Table.  Diffusion  of  Case? 39 

CHAPTER  VIII 
BAROMETER 

The  Aneroid  and  Mercurial  Barometers.  Atmospheric  Pres- 
sure. Use  of  Barometer  in  Mines.  Use  of  Barometer  in 
Determining  Altitudes.  Table  of  Altitudes.  Barometer 
Indications.  Effect  of  Temperature  and  Pressure  on  Vol- 
ume of  Gases.  Charles'  Law.  Boyle's  Law.  Absolute 
Zero.  Absolute  Temperature.  Calculation  of  the  Weight 
of  a  Gas  at  Different  Temperatures  and  Pressures 52 


CHAPTER    IX 

GASES 

Acetylene  Gas.  Safety  Lamps.  Occlusion  of  Gases.  Properties. 
Physical  and  Chemical  Properties  of  Air.  Carbon  Monoxide. 
Carbon  Dioxide,  how  Produced.  Effect  of  Black  Damp 
on  Atmospheres  Containing  Fire  Damp.  Marsh  Gas. 
Detection  of  Fire  Damp.  Ethane.  Ethylene.  Sulphurated 
Hydrogen.  Table  of  Chemical  Analysis  of  Mine  Air 68 


CONTENTS  vii 

CHAPTER  X 

SPECIFIC  HEAT 

PAGE 

Heat  Capacity.    Table  of  Specific  Heat.    Measurement  of  Specific 

Heat 82 

CHAPTER  XI 
MINE  VENTILATION 

Ventilation.     Pressure     Defined.     Water     Gauge.     Calculations. 

Laws  of  Friction.     Table  of  Velocity  Pressure 87 

CHAPTER  XII 
MINE  VENTILATION 

Natural  Ventilation.  Water  and  Steam  Jet  System  of  Ventila- 
tion. Furnace  Ventilation.  Ventilation  by  Means  of  Fan. 
Robinson  Fan.  Table  of  Dimensions  and  Volumes.  The 
Sirocco  Fan.  Table  of  Quantities.  Jeffrey  Fan.  Theoreti- 
cal Water  Gauge.  Cost  per  Horse-power.  Installation  of 

3  Fan.  Motive  Column.  Splitting  of  Air  Currents.  Regula- 
tors. Resistance 104 

CHAPTER  XIII 
FORMULAS 

Formulas     and     Their     Application.     Coefficient     of     Friction. 

Transposition  of  Formulas 141 

CHAPTER  XIV 
MINE  FIRES 

Suggestions  to  Prevent  Mine  Fires.  Suggestions  for  Guidance  after 
a  Fire  or  Explosion.  Sealing  a  Mine  Fire.  Effect  Produced 
by  Sealing  a  Mine  Fire.  Useful  Tables  and  Formulas 152 

SUMMARY.  .  .175 


CHEMISTRY  OF  MINING  AND  MINE 
VENTILATION 


CHAPTER  I 
PROPERTIES   OF  MATTER 

1.  Matter. — The  term  "  matter  "  is  one  which  has  a 
very  wide  meaning.     To  say  that  "  matter  is  that  which 
occupies  space/'   adds  little  if  anything  to  our  common 
understanding   of   the   term.     Matter   includes   all   things 
which  exist   of  which  we  can  become  aware  by  our  sense 
of  sight,  touch,  taste,  smell  and  hearing.     There  are  numer- 
ous different  kinds  of  matter  and  they  are  usually  indi- 
cated by  the  term  SUBSTANCE.     Thus  air,  coal,  iron,  wood, 
water,   etc.,   are  different  kinds  of  matter,   also  different 
substances. 

Matter  may  be  classified  under  three  distinct  heads: 
namely,  solids,  liquids,  and  gases. 

2.  Properties  of  Matter. — Matter  is  possessed  of  certain 
peculiar  qualities  which  serve  to  define  i't.     These  prop- 
erties are  either  GENERAL  or  SPECIFIC. 

General  Properties  are  those  found  in  all  matter,  such 

as     EXTENSION,    DIVISIBILITY,    IMPENETRABILITY,     POROSITY, 
INERTIA,  INDESTRUCTIBILITY. 

Specific  properties  are  those  found  in  certain  kinds  of 
matter  only,  such  as  DUCTILITY,  HARDNESS,  MALLEABILITY. 

3.  Extension. — All  bodies  have  extension  in  three  direc- 


2  MINING  kft'D  'MTNE  VENTILATION 

tions,  and  occupy  space,  commonly  called  length,  breadth, 
and  thickness.  The  absence  of  any  one  of  these  three 
dimensions  is  sufficient  to  prove  that  the  thing  under 
consideration  is  not  matter.  Hence,  lines  and  surfaces 
are  not  bodies  in  the  physical  sense. 

4.  Impenetrability. — This  property  means  that  no  two 
bodies,  however  small,  can  occupy  the  same  space  at  the 
same  time.     When  a  stone  is  dropped  into  a  tumbler  full 
of  water  some  of  the  water  overflows.     If  the  volume  of  the 
stone  is  one  cubic  inch,  exactly  one  cubic  inch  of  water 
is  displaced.     A  nail  driven  into  a  block  of  wood  pushes  the 
substance  of  the  wood  together;  the  wood  now  occupies  only 
part  of  the  space  it  originally  occupied. 

5.  Porosity. — All   matter   is   pprous,   that   is,   the  par- 
ticles of  matter  of  which  a  body  is  composed  do  not  fill 
the  entire  volume  occupied  by  it.     The  molecules  of  a  body 
are  spherical  therefore  there  is  space  between  them.     Hence, 
a  blotter  will  absorb  ink,  lime  will  absorb  carbon  dioxide, 
without  change  of  volume.     Glass,   iron   and   other   hard 
substances  are  known  to  be  porous. 

6.  Compressibility. — The  compressibility  of  a  substance 
is  evidence  of  its  porosity.     Gases  are  very  compressible, 
solids  to  a  much  less  degree,  and  liquids  are  almost  incom- 
pressible.    If  the  pressure  upon  a  gas  is  doubled,   tem- 
perature  remaining   the   same,    its   volume   is   diminished 
one-half.     While    changing    the    pressure    upon    water    in 
the  same  manner  its  volume  diminishes  only  ^-Wir- 

7.  Indestructibility. — Matter   can   be  made  to   assume 
different  forms  as  the  result  of  PHYSICAL  and  CHEMICAL 
CHANGES.     Sometimes  the  change  is  only  temporary,   as 
in  the  freezing  of  water  or  in  the  melting  of  iron.     Such 
changes  are  called  PHYSICAL  CHANGES.     In  this  case  the 
substance  does  not  lose  its  identity,  but  may  be  restored 
by  merely  mechanical  means  to  its  original  state  when  the 


PROPERTIES  OF  MATTER  3 

original  temperature  is  resumed.  But  often  the  change  is 
permanent,  as  in  the  burning  of  coal,  the  rusting  of  metals; 
in  this  case  the  original  cannot  be  restored  by  mechanical 
means.  Changes  in  which  a  substance  thus  loses  its 
identity  are  called  CHEMICAL  CHANGES. 

Matter  may  be  changed  by  crushing,  burning,  cooking 
and  mixing  with  other  substances;  but  MATTER  ITSELF 
CANNOT  BE  DESTROYED.  The  number  of  atoms  in  the  uni- 
verse is  exactly  the  same  now  as  it  was  hundreds  of  years 
ago. 

8.  Divisibility. — Divisibility  is  that  property  of  matter 
which  indicates  that  a  body  can  be  divided  into  smaller 
parts  without  changing  the  matter  of  which  it  is  composed. 

9.  Inertia. — Inertia    is    the   tendency    possessed    by    a 
body  to  remain  at  rest  or  in  motion.     A  body  cannot  put 
itself  in  motion  or  bring  itself  to  rest.     To  do  either,  it 
must  be  acted  upon  by  some  force  outside  of  itself. 

Use  is  made  of  inertia,  as  in  driving  on  the  head  of 
a  hammer  by  striking  the  end  of  the  handle.  The  violent 
jar  to  a  water  pipe  on  suddenly  closing  the  faucet  is  due 
to  the  inertia  of  the  stream. 

10.  Elasticity. — This  property  exhibited  by  matter  indi- 
cates that  if  a  body  be  distorted  within  its  elastic  limit 
it  will  resume  its  original  form  when  the  distorting  force 
is  removed. 

Apply  pressure  to  a  rubber  ball,  stretch  a  rubber  band, 
bend  a  piece  of  steel.  In  each  case  the  original  form  is 
changed,  but  the  body  readily  recovers  from  the  strain 
on  the  removal  of  the  stress,  and  will  resume  its  original 
form  if  not  distorted  beyond  its  elastic  limit. 

All  bodies,  whether  solids,  liquids,  or  gases,  when  reduced 
in  volume  by  addition  of  pressure,  regain  or  partly  regain 
their  volume  when  this  added  pressure  is  removed.  A 
piece  of  wood  may  be  compressed  to  half  its  volume  and 


4  MINING  AND  MINE  VENTILATION 

when  released  it  expands,  but  does  not  nearly  return  to 
its  original  volume.     It  has  been  compressed  beyond  its 

ELASTIC    LIMIT. 

Liquids  and  gases  have  no  ELASTIC  LIMIT.  No  amount 
of  compression  can  permanently  change  their  volume; 
they  always  return  to  their  original  volume  when  the  dis- 
torting pressure  is  removed. 

HOOKE'S  LAW. — Whenever  the  forces  that  produce  dis- 
tortions in  any  body  are  within  the  elastic  limit,  the  distor- 
tions produced  are  directly  proportional ,  to  the  forces  that 
produce  them.  That  is,  if  a  one-pound  weight  be  suspended 
from  a  spring  balance,  and  the  stretch  of  the  spring 
measured,  after  which  a  four-pound  weight  be  suspended 
in  the  same  manner,  it  will  be  found  that  the  four-pound 
weight  will  stretch  the  spring  four  times  that  of  the  one- 
pound  weight. 

11.  Cohesion. — When  we  try  to  break  a  piece  of  wood, 
we  are  conscious  of  a  force  tending  to  hold  the  parts  to- 
gether. Hence,  COHESION  gives  to  solids  their  stabilty  of 
form.  All  bodies  are  made  up  of  small  particles  called 
molecules,  and  COHESION  is  the  natural  attraction  that  these 
particles  have  for  each  other.  It  is  measured  by  the  force 
required  to  pull  them  apart. 

The  COHESION  is  not  as  strong  in  liquids  as  in  solids. 
In  fact,  it  is  not  sufficient  to  maintain  the  form,  yet  the 
molecules  in  a  drop  of  water  hanging  from  the  roof  of 
a  mine  have  sufficient  attraction  for  each  other  to  support 
the  weight  of  the  drop,  unless  it  becomes  so  large  that 
the  weight  is  greater  than  the  COHESION. 

In  gases  the  molecules  are  so  far  apart  that  there  is 
very  little  COHESION  between  them.  On  account  of  this 
gases  cannot  be  moved  by  a  pull,  they  must  be  moved 
by  a  push  or  pressure.  Air  cannot  be  pulled  through  the 
airways  of  a  mine;  it  is  moved  by  reason  of  pressure. 


PROPERTIES  OF  MATTER  5 

Likewise  water,  must  be  moved  by  pressure;    its  force  of 
COHESION  is  not  sufficient  to  allow  it  to  be  pulled. 

QUESTIONS 

1.  What  different  forms  can  water  be  made  to  assume 
by  changing  its  temperature? 

2.  Why  can  the  head  of  a  hammer  be  driven  on  the 
handle  better  by  striking  the  end  of  the  handle  against 
a  stone  than  by  striking  the  head  against  the  stone? 

3.  How  would  you  find  the  volume  of  a  piece  of  coal 
by  displacement? 

4.  Under    how    many    heads    is    "  matter "    classified? 
What  are  they? 

5.  Can  matter  be  destroyed?  • 

6.  What  is  Hooke's  law  of  elasticity?     Give  an  example 
of  its  application. 

7.  If  the  pressure  upon  a  volume  of  gas  is  doubled, 
what  change  takes  place  in  the  volume  of  the  gas,  and  to 
what  extent? 

8.  If  the  pressure  upon  a  volume  of  water  is  doubled, 
to  what  extent  is  the  volume  reduced? 

9.  What  is  meant  by  the  term  "  inertia  "? 

10.  If  a  hoisting  rope  on  a  shaft  is  stretched  beyond 
its  elastic  limit  will  the  rope  recover  from  the  strain  after 
the  stress  is  removed? 

11.  What  do  you  understand  by  the  term  "  COHESION  "? 

12.  Why  cannot  air  be  pulled  through  a  mine? 

13.  (a)  If  a  stone,  one-half  cubic  foot  in  volume,  be 
dropped  in  a  vessel  filled  with  water,   how  much  water 
is  displaced?     (6)  If  water  weighs  62.5  Ibs.  per  cubic  foot, 
what  weight  of  water  does  the  stone  lift?     (c)  How  much 
less  will  this  stone  weigh  under  water? 


CHAPTER  II 
MOTION,   VELOCITY  AND   FORCE 

12.  Motion. — Motion  is  a  change  of  place,  and  is  the 
opposite  of  rest.     Or,  motion  is  the  change  in  the  relative 
position  of  a  body  with  respect  to  some  point  or  place. 

When  a  body  moves  in  a  path  which  constantly  changes 
in  direction,  it  is  said  to  move  in  a  curve.  Strictly  speaking 
all  bodies  moving  in  space  are  constantly  changing  in  di- 
rection. A  ball  dropped  from  a  balloon  moves  toward  the 
center  of  the  earth,  but  as  the  earth  itself  is  moving  around 
the  sun,  the  path  of  the  ball  must  be  in  a  curving 
direction.  For  this  reason  a  stone  dropped  into  a  deep 
shaft  will  strike  the  side  before  it  reaches  the  bottom; 
however,  for  all  practical  purposes  the  slight  curvature 
referred  to  may  be  neglected. 

13.  Newton's  First  Law  of  Motion. — Every  body  con- 
tinues in  its  state  of  rest,  or  uniform  motion  in  a  straight 
line,  except  in  so  far  as  it  may  be  compelled  by  force  to 
change  that  state.     Newton  states  in  this  law  that  a  state 
of  uniform  motion  is  just  as  natural  as  a  state  of  rest. 
This  is  at  first  difficult  to  realize,  because  rest  seems  the 
natural  state  and  motion  the  enforced  one.     But  difficulty 
is  at  once  dispelled  as  soon  as  one  begins  to  inquire  into 
the  causes  that  hinder  the  movement  of  a  body  artificially 
set  in  motion. 

A  rifle  ball  soon  stops  because  resistance  of  the  air 
continually  lessens  its  speed,  and  finally  gravity  draws 
it  down  upon  the  earth. 

A  baseball  rolling  upon  a  level  field  soon  stops  because, 

6 


MOTION,  VELOCITY  AND  FORCE  7 

in  moving  forward,  it  must  repeatedly  rise  against  the 
attraction  of  gravity  in  order  to  pass  over  minor  obstacles 
such  as  pebbles  and  mounds.  There  is  also  much  surface 
friction. 

If  it  were  possible  to  fire  a  rifle  ball  into  space  very 
remote  from  the  attraction  of  the  solar  system,  it  would 
travel  for  ages,  because  no  attraction  or  atmosphere  would 
resist  its  progress. 

14.  Newton's  Second  Law  of  Motion. — The  second  law 
reads:  "  Change  of  motion  is  proportional  to  force  applied 
and  takes  place  in  the  direction  of  the  straight  line  in  which 
the  force  acts.  Thus  if  a  cannon  ball  is  shot  horizontally 
along  a  level  surface  and  another  ball  allowed  to  drop 
vertically  from  the  mouth  of  the  cannon,  they  will  both 
strike  the  surface  at  the  same  instant.  This  shows  that 
the  force  which  gives  the  cannon  ball  its  horizontal  move- 
ment has  no  effect  on  the  vertical  force,  which  compels 
both  balls  to  fall  to  the  surface." 

16.  Newton's  Third  Law  of  Motion. — To  every  action 
there  is  always  an  equal  and  opposite  reaction. 

To  illustrate,  in  Newton's  own  words:  "  If  you  press 
a  stone  with  your  finger  the  finger  is  also  pressed  by  the 
stone.  And  if  a  horse  draws  a  stone  tied  to  a  rope  the 
horse  will  be  equally  drawn  back  toward  the  stone;  for 
the  stretched  rope,  in  one  and  the  same  endeavor  to  relax 
or  unstretch  itself,  draws  the  horse  as  much  toward  the  stone 
as  it  draws  the  stone  toward  the  horse."  There  must  be, 
and  always  is,  a  pair  of  forces  equal  and  opposite. 

Horse  and  stone  advance  as  a  unit  because  the  mus- 
cular power  of  the  horse  exerted  upon  the  ground  exceeds 
the  resistance  of  the  stone. 

In  springing  from  a  boat  we  must  exercise  caution, 
because  the  force  necessary  to  shove  the  body  out  of  the 
boat  reacts  and  tends  to  push  the  boat  from  the  shore. 


8  MINING  AND  MINE  VENTILATION 

16.  Velocity. — Velocity  is  the  rate  of  motion.     When 
a  body  moves  over  equal  spaces  in  successive  equal  times 
its  motion  is  uniform;  if  it  travels  unequal  spaces  in  suc- 
cessive equal  times  its  motion  is  variable.     For  example, 
an  engine  controlled  by  a  governor  runs,  practically  speak- 
ing,  with   a   uniform   velocity.      On  the   other   hand  the 
motion  of  a  stone  falling  down  a  shaft  is  variable,  for  its 
speed  is  increasing  each  second  as  it  descends. 

17.  Force. — Force  may  be  denned  as  that  which  tends 
to  produce  motion  or  to  hinder  the  motion  of  a  body. 

When  two  forces  act  on  a  body  along  the  same  line 
and  in  the  same  direction  the  resultant  force  is  simply  their 
sum,  and  it  acts  in  the  same  direction  as  the  forces.  The 
same  is  true  when  there  are  more  than  two  forces  acting 
in  the  same  direction. 

When  two  forces  act  on  a  body  along  the  same  line, 
but  in  opposite  directions,  their  resultant  equals  their  dif- 
ference, and  it  acts  in  the  direction  of  the  greater  force.. 

For  example,  if  an  engine  pulls  on  a  train  of  cars  with 
a  force  of  3000  Ibs.  and  another  pushes  at  the  back  with 
a  force  of  4000  Ibs.,  the  resultant  force  applied  to  move 
the  train  is  7000  Ibs.  But  if  one  pulls  with  a  force  of  1000 
Ibs.  in  one  direction  and  the  other  with  a  force  of  800  Ibs. 
in  the  other  direction,  the  resultant  force  tending  to  move 
the  train  forward  is  only  200  Ibs.  Therefore,  the  resultant 
of  two  forces  acting  in  the  same  straight  line,  but  in  op- 
posite directions,  is  the  difference  of  the  given  forces  and 
acts  in  the  direction  of  the  greater. 

18.  Parallelogram   of   Forces. — Forces   may   be   repre- 
sented by  lines  drawn  to  the  same  scale. 

EXAMPLE. — Suppose  the  force  E  (Fig.  1),  to  be  3  Ibs. 
and  acting  along  the  line  AC  toward  C  and  at  right  angles 
to  the  force  F,  which  is  2  Ibs.  and  acting  toward  B. 

Represent  force  E  by  line  AC  drawn  to  scale,  say  one 


MOTION,  VELOCITY  AND  FORCE  9 

inch  equals  2  Ibs.,  in  like  manner  draw  AB  representing 
force    F.     Complete    the    parallelogram    by    drawing    the 
dotted  lines  CD  and  BD    (parallel 
to  AB  and  AC  respectively). 

The  magnitude  and  direction  of 
the  resultant  of  the  two  forces  E 
and  F  will  be  equal  to  G  and  in  the 
direction  of  line  AD. 

When  the  angle  is  a  right  angle, 
as  in  the  present  case,  the  diagonal 
AD  is  the  hypotenuse  of  the  right- 

angled  triangle  ACD;  the  force  of  G,  being  equal  to  the 
hypotenuse,  is  found  as  follows: 


=  3.606. 

If  the  angle  is  not  a  right  angle,  the  resultant  can  be 
found  by  measurement  or  by  the  principles  of  trigonom- 
etry. 

EXAMPLE.  —  Suppose  a  sheave  wheel  and  hoisting  drum, 
as  shown  in  Fig.  2,  the  rope  passing  from  the  drum  around 
the  sheave  to  the  cage  and  making  an  angle  of  30°  with 
a  vertical  line.  If  the  weight  of  the  cage  is  10  tons,  (a) 
Wha,  force  will  then  be  on  the  shaft  of  the  sheave  wheel? 
(6)  In  what  direction  will  the  resultant  force  act? 

Solution.  —  As  the  weight  of  the  load  is  10  tons  the 
tension  at  any  point  along  the  rope  is  10  tons,  consequently 
there  is  a  force  of  10  tons  acting  from  the  sheave  to  the 
drum  and  also  a  force  of  10  tons  acting  from  the  sheave 
to  the  load. 

Produce  the  lines  AB  and  BC  to  D,  thus  we  have  the 
point  of  application  and  direction  of  the  forces.  Using 
a  scale  of  1  inch  =  5  tons,  lay  off  from  D  a  distance  equal 
to  2  inches  or  10  tons  along  lines  DA  and  DC,  then  com- 


10 


MINING  AND  MINE  VENTILATION 


plete  the  parallelogram  by  drawing  line  FE  parallel  to 
line  DC  and  line  GE  parallel  to  line  DA.  Next  draw 
line  DE,  which  will  be  the  direction  in  which  the  resultant 
force  acts,  and  the  length  of  DE,  using  the  same  scale 
as  given  above,  will  equal  19.5;  therefore  if  the  parts 


FIG.  3. 


are  not  in  motion  the  weight  on  the  shaft  of  the  sheave 
wheel  is  19.5  tons. 

Velocity  can  also  be  represented  graphically.  For 
example,  if  a  man  rows  a  boat  across  a  stream  with  a  uni- 
form velocity  of  4  miles  per  hour,  and  the  stream  flows 
with  a  uniform  velocity  of  3  miles  per  hour,  the  direction 
taken  by  the  boat  can  be  determined  by  the  velocities. 
If  the  boat  starts  from  A,  Fig.  3,  the  path  of  the  boat 


MOTION,  VELOCITY  AND  FORCE  11 

may  be  found  by  laying  off  AB  to  represent  the  velocity 
of  4  miles  per  hour,  and  BC  to  represent  the  velocity  of 
the  stream,  3  miles  per  hour.  Then  AC  will  be  the  direction 
the  boat  will  take.  If  the  width  of  the  stream  is  known 
line  AC  can  be  readily  found. 

QUESTIONS 

1.  Find  the  resultant  of  30  Ibs.  north  and  40  Ibs.  east. 
Represent  forces  and  resultant  graphically. 

2.  What  is  motion? 

3.  Why  will  a  stone  not  fall  down  a  deep  shaft  without 
striking  the  side  of  the  shaft? 

4.  What  is  Newton's  first  law  of  motion? 

5.  If  a  man  rows  a  boat  across  a  river  at  the  rate  of 

2  miles  per  hour  and  the  river  is  flowing  at  the  rate  of 

3  miles  per  hour,  show  graphically  the  direction  of  the  boat. 

6.  If  a  cannon  ball  is  shot  horizontally  along  a  level 
surface  and  another  ball  is  allowed  to  drop  from  the  mouth 
of  the  cannon  at  the  same  instant,  neglecting  the  resistance 
offered  by  the  air,  which  will  strike  the  ground  first? 

7.  A  rope  runs  from  a  hoisting  drum  at  an  angle  of 
45°  and   passes    over   a   sheave   wheel   which   is   directly 
over  the  center  of  the  shaft;   on  the  shaft  end  of  the  rope 
there  is  a  cage  weighing  8  tons;  what  is  the  force  on  the 
sheave  wheel? 

8.  What  is  velocity? 

9.  If  two  forces  act  on  a  body  along  the  same  line  and 
in  the  same  direction,  each  force  is  equal  to  100  pounds, 
what  is  the  resultant  force? 

10.  If  two  forces  act  on  a  body  along  the  same  line, 
but  in  opposite  direction,  one  force  is  equal  to  50  Ibs.,  and 
the  other  100  Ibs.,  what  is  the  resultant  force  and  in  what 
direction  does  it  act? 


CHAPTER  III 
GRAVITATION 

19.  The  power  called  gravitation  is  the  name  given  to 
the  attractive  force  between  different  bodies.     It  is  this 
power  that  prevents  the  earth,  moon,  and  other  heavenly 
bodies  from  swerving  outside  their  paths  in  space.     The 
force  of  the  great  law  of  gravitation  is  so  evenly  and  con- 
stantly applied  that,  hundreds  of  years  in  advance,  the  places 
of  planets  in  space  and  the  exact  hour,  minute  and  second 
when  eclipses  will  happen  can  be  foretold.     Regardless  of 
this  what  gravitation  is  is  not  yet   known.     It   is   only 
known  that  it  acts  instantaneously  over  distances  whether 
great  or  small,  and  no  known  substance  interposed  between 
two    bodies    has    power    to    interrupt    their    gravitational 
tendency  toward  each  other. 

While  the  term  GRAVITATION  is  applied  to  universal 
attraction  existing  between  particles  of  matter,  the  more 
restricted  term  GRAVITY  is  applied  to  the  attraction  that 
exists  between  the  earth  and  bodies  upon  or  near  its 
surface. 

20.  Newton's  Law  of  Gravitation. — The  law  may   be 
stated  as  follows:    First,  that  every  particle  of  matter  in  the 
universe  attracts  every  other  particle  directly  as  its  mass  or 
quantity  of  matter.     Second,  that  the  amount  of  this  attrac- 
tion increases  in  proportion  as  the  square  of  the  distance 
between  the  bodies  decreases. 

21.  Weight. — The  weight  of  a  body  is  the  measure  of 
the  attraction  that  exists  between  the  earth  and  that  body. 

Bodies  weigh  most  at  the  surface  of  the  earth.     Below  the 

12 


GRAVITATION  13 

surface  the  weight  decreases  as  the  distance  to  the  center 
decreases. 

Above  the  surface  the  weight  decreases  as  the  square  of 
the  distance  increases. 

According  to  the  above  rule  a  body  that  weighs  100 
Ibs.  at  the  surface  of  the  earth  will  weigh  nothing  at  the 
center,  the  body  being  attracted  equally  in  all  directions. 

EXAMPLE. — If  the  radius  of  the  earth  is  4000  miles 
and  a  body  on  the  surface  weighs  200  Ibs.,  what  will  it 
weigh  1000  miles  below  the  surface? 

Solution. — At  3000  miles  from  the  center  it  will  weigh 
150  Ibs.  4000-1000  =  3000  and  4000  :  3000 : :  200  :  150. 

EXAMPLE. — If  the  same  body  was  carried  1000  miles 
above  the  surface  or  5000  miles  from  the  center  of  the 
earth,  it  will  weigh  128  Ibs. 

50002  :  40002::200  :  128. 

Therefore  it  can  be  seen  that  the  weight  of  a  body  at  any 
place  is  the  attraction  between  it  and  the  earth  at  that 
place.  If  two  bodies  have  the  same  weight  at  a  given 
place  they  must  also  have  the  same  mass. 

THE  DIRECTION  OF  THE  EARTH'S  ATTRACTION. — When 
a  plumb  line  is  suspended  from  a  certain  point,  the  line  is 
said  to  be  vertical.  Vertical  lines  suspended  at  different 
points  on  the  earth's  surface,  if  continued,  would  meet 
approximately  at  the  earth's  center,  hence  they  are  never 
strictly  parallel,  though  practically  so,  provided  they  are 
near  to  each  other. 

22.  Laws  of  Falling  Bodies. — A  body  that  is  moving 
under  the  influence  of  gravity  alone  is  a  FREELY  FALLING 
BODY.  This  condition  can  be  obtained  only  in  a  vacuum, 
as  the  air  constantly  offers  a  resistance  to  the  passage 
of  any  body  through  it. 


14  MINING  AND  MINE  VENTILATION 

If  an  iron  ball  and  a  piece  of  paper  are  dropped  from 
the  same  height,  the  ball  will  strike  the  ground  first.  This 
is  not  because  the  ball  is  heavier,  but  because  the  resistance 
of  the  air  has  a  greater  retarding  effect  upon  the  paper. 
If  the  same  ball  and  paper  were  placed  in  a  glass  tube 
from  which  all  the  air  has  been  extracted,  and  allowed 
to  fall  as  before,  they  would  both  fall  with  the  same  veloc- 
ity and  reach  the  bottom  at  the  same  instant. 

Some  bodies  do  not  fall,  but  ascend.  For  example, 
a  balloon  in  the  air  or  a  cork  under  water.  This  is  not 
because  the  earth  does  not  attract  them,  but  because  an 
equal  bulk  of  the  air  or  water  immediately  above  the 
body  contains  a  greater  mass  of  matter  and  is  therefore 
more  strongly  attracted  by  the  earth  than  the  body 
itself.  The  balloon  and  the  cork  are,  by  reason  of  the 
greater  mass  of  air  and  water  above  them,  consequently 
exchanging  places,  the  greater  mass  sinking  and  forcing 
the  smaller  mass  upward. 

23.  Effect  of  a  Constant  Force. — Whenever  a  body  is 
falling  freely  under  the  influence  of  gravity  only,  regard- 
less of  its  size,  it  will  fall  in  the  first  second  16.08  ft.,  and 
its  velocity  at  the  end  of  the  first  second, will  be  32.16 
ft.  per  second.  This  latter  number  is  always  denoted 
by  g,  and  is  the  constant  accelerating  force  exerted  on  all 
freely  falling  bodies.  It  should  be  understood  that  g 
varies  at  different  points  on  the  earth's  surface,  it  being 
a  little  greater  at  the  poles  than  at  the  equator.  Careful 
experimenting  has  determined  that  at  New  York  the 
acceleration  of  a  freely  falling  body  is,  as  stated,  32.16  ft. 

The  distance  through  which  a  freely  falling  body  will 
move  in  a  given  time  is  equal  to  16.08  multiplied  by  the 
square  of  the  time  in  seconds. 

EXAMPLE. — The  distance  a  body  will  fall  in  2  seconds 
equals  16,08  times  22  or  16.08  times  4  or  64.32  ft.  In 


GRAVITATION  15 

3  seconds  it  will  fall  16.08  times  32  or  16.08  times  9,  or 
144.72  ft. 

24.  Formulas  for  Falling  Bodies.  —  The  relations  ex- 
pressed by  these  formulas  are  usually  known  as  the  laws 
of  falling  bodies.  They  apply  strictly  to  those  bodies 
which  fall  without  being  hindered  by  the  air  or  anything 
else. 

Let  t  —  number  of  seconds  a  body  falls; 
v  =  velocity  at  the  end  of  the  time; 
h  =  distance  that  a  body  falls  ; 

g  =  force  of  gravity,  or  accelerating  force  due  to  the 
attraction  of  the  earth  (0  =  32.16). 

EXAMPLE.  —  If  it  requires  10  seconds  for  a  stone  to  fall 
down  a  shaft,  what  is  its  velocity  at  the  end  of  the  10th 
second,  assuming  that  the  air  offers  no  resistance? 

Solution.—  v  =  gt  or  32.16X10  =  321.6  ft.  per  second. 

EXAMPLE.  —  If  the  shaft  mentioned  in  the  above  problem 
is  1608  ft.  deep,  how  long  will  it  take  a  stone  to  fall  from 
top  to  bottom? 


Solution.  —  1  =  —   or 


=  \  — 
\  flf 


J2h       / 
=  \  —  =  \ 
\  g      \ 


1608X2 

or  10  seconds. 


oo  ^ 
g      \    32.16 

EXAMPLE.  —  If  a  falling  body  has  a  velocity  of  321.6 
ft.  per  second,  how  long  had  it  been  falling  at  that  instant? 

v  321.6 

solution.  —  t  =  —.     t  =  00    g  =  10  seconds. 
g  32.16 

EXAMPLE.  —  A  stone  dropped  down  a  shaft  has  a  velocity 
of  321.6  feet  when  it  strikes  the  bottom,  how  deep  is  the 
shaft? 


16  MINING  AND  MINE  VENTILATION 

Solution.  — 
v2     321.6X321.6     103426.56 


2g        2X32.16 


=1608  ft.,  depth  of  shaft. 


EXAMPLE.  —  A  body  falls  down  a  shaft  which  is  1608 
feet  deep,  what  will  be  its  velocity  at  the  end  of  the  fall? 

Solution.  —  v  =  \/2gh. 

v=v/2X32.16X  1608  =  321.6  ft.,  velocity  per  sec. 

EXAMPLE.  —  How  far  will  a  body  fall  in  10  seconds? 
Solution.—  h  =  %gt2  or  h  =  16.08  Xt2. 

16.08X100  =  1608  ft. 

EXAMPLE.  —  If  a  ball  is  thrown  vertically  upward  with 
an  initial  velocity  of  321.6  ft.  per  second,  (a)  how  long 
a  time  will  elapse  before  it  reaches  the  earth  again? 

v2 
Solution.  —  h  =  -=-, 


h  =  =  1608  feet. 

To  find  the  time  required  to  reach  a  height  of  1608  ft. 

v          321.6 

£  =  -  =  £  =  ^-^  =  10  seconds. 
g  62.1D 

As  it  will  take  the  same  length  of  time  for  the  ball 
to  fall  to  the  earth  the  total  time  consumed  in  going  both 
directions  will  be  10X2  =  20  seconds.  Ans. 


GRAVITATION  17 

QUESTIONS 

1.  If  a  stone  thrown  upward  returns  to  the  ground  in 
4  seconds,  how  high  does  it  ascend? 

2.  A  cannon  ball  is  fired  horizontally  from  the  top  of 
a  cliff  200  ft.  high.     In  how  many  seconds  will  it  strike 
the  plain  at  the  foot  of  the  cliff? 

3.  Define  (a)  gravitation;  (6)  gravity. 

4.  What  is  Newton's  law  of  gravitation? 

5.  If  an  iron  ball  weighs  100  Ibs.  on  the  surface  of  the 
earth,  what  will  it  weigh  1000  miles  below  the  surface? 

6.  What  will  a  100-lb.  ball  weigh  1000  miles  above  the 
surface  of  the  earth?      What  will  it  weigh  at  the  center 
of  the  earth? 

7.  If  two  plumb  lines  suspended  at  different  points  on 
the  earth's  surface  were  projected  through  the  earth  where 
would  they  meet? 

8.  Will  an  iron  ball  weighing  2  Ibs.  fall  with  a  greater 
velocity  than  a  smaller  ball  weighing  1  lb.? 

9.  How  far  will  a  freely  falling  body  fall  in  the  first 
second?    What  will  be  its  velocity  at  the  end  of  the  first 
second? 

10.  A  rifle  ball  is  shot  vertically  upward  with  a  velocity 
of  1500  ft.   per  second.     In  what  time  will  it  reach  the 
ground,  neglecting  the  friction  of  the  air? 

11.  How  far  must  a  ball  fall  in  order  to  acquire  a  velocity 
of  321.6  ft.  per  second? 

12.  A  stone  dropped  down  a  shaft  strikes  the  bottom 
in  4  seconds.     What  is  the  depth  of  the  shaft? 

13.  A  stone  falls  down  a  shaft  400  ft.  deep.     In  what 
time  will  it  strike  the  bottom? 

14.  Explain  what  is  meant  by  accelerating  force,  and 
at  what  velocity  will  it  cause  a  freely  falling  body  to  move 
at  the  end  of  the  first  second  of  its  fall? 


18  MINING  AND  MINE  VENTILATION 

15.  Why  does  a  balloon  ascend  in  the  air? 

16.  Why  does  not  the  attraction  of  the  earth  cause 
fire  damp  to  lodge  in  low  places  in  a  coal  mine? 

17.  When  we  speak  of  the  weight  of  a  body  to*  what 
do  we  refer? 

18.  Why  is  it  a  body  has  no  weight  at  the  center  of 
the  earth? 

19.  A  stone  1  cubic  foot  in  volume  and  weighing  180 
Ibs.  is  under  water.     If  a  man  lifts  the  stone  while  under 
water  what  weight  does  he  lift? 

20.  What  is  the  velocity  of  a  freely  falling  body  at  the 
end  of  12  seconds? 

21.  If   a   stone   thrown   vertically   upward   reaches   its 
maximum  height  in  2  seconds  in  how  many  seconds  will 
it  fall  to  the  starting  point? 


CHAPTER    IV 
LIQUIDS  AND  LIQUID   PRESSURE 

25.  Liquids  offer  great  resistance  to  forces  tending  to 
diminish   their   volume.     Water   is   reduced   only   0.00005 
of  its  volume  by  a  pressure  of  one  atmosphere.     A  gas  is 
reduced  to  one-half  its  volume  by  the  same  pressure. 

The  case  of  sea-water  is  of  special  interest  on  account 
of  the  influence  of  its  compressibility  upon  the  ocean  level. 
Tait,  in  his  extended  investigation  of  this  property  in 
connection  with  the  deep-sea  exploration,  computed  the 
loss  of  volume  due  to  the  compression  of  each  layer  of 
ocean  water  by  the  superincumbent  mass,  and  found  the 
level  of  the  sea  to  be  more  than  600  ft.  below  that  which 
would  exist  in  the  case  of  a  strictly  incompressible  fluid. 

26.  Pressure  on  the  Side  of  a  Vessel. — When  a  liquid 
is  contained  in  a  vessel,  the  sides  being  vertical,  the  pres- 
sure at  any  point  of  a  side  depends  upon  its  distance  from 
the  surface  of  the  liquid.     The  total  pressure  on  the  sides 
of  the  vessel  is  the  sum  of  all  these  pressures,  which  vary 
from  zero  at  the  surface  to  a  maximum  at  the  bottom. 

RULE. — The  pressure  of  a  liquid  upon  any  submerged 
surface  is  equal  to  the  weight  of  a  column  of  the  liquid 
having  the  area  of  the  surface  for  its  baseband  the  depth 
of  the  center  of  gravity  of  the  given  surface,  below  the 
surface  of  the  liquid,  for  its  height.  This  rule  applies  to 
all  submerged  surfaces  whether  vertical,  horizontal  or 
inclined,  plane  or  curved.  If  the  surface  is  the  horizontal 
base  of  the  vessel  the  height  of  the  column  will  be  the  total 
depth  of  the  liquid. 

19 


20  MINING  AND  MINE  VENTILATION 

EXAMPLE. — A  vessel  is  filled  with  water.  Its  base  is 
2  ft.  by  2  ft.  and  5  ft.  high.  What  is  the  total  pressure 
on  the  base? 

Solution.— 5  X  (2  X  2)  X  62.5  =  1250  Ibs.  A  cubic  foot  of 
water  weighs  about  62.5  Ibs.  or  1000  ozs. 

NOTE. — In  plane  surfaces  the  center  of  gravity  is  the 
center  of  area.  The  center  of  gravity  of  a  triangle  is  a 
point  two-thirds  of  the  distance  from  any  angle  to  the 
middle  point  of  the  opposite  side.  The  pressure  per  square 
inch  due  to  any  head  of  water  may  be  found  by  multi- 
plying the  head  or  vertical  height  of  the  water  by  .434. 

This  number  is  obtained  as  follows:  62. 5 -j- 144  =  .434.     * 

EXAMPLE. — What  is  the  pressure  per  square  inch  on 
the  bottom  of  a  column  standing  full  of  water,  the  ver- 
tical height  being  500  ft.? 

Solution.— .434X500  =  217  Ibs. 

27.  Specific  Gravity,  or  Relative  Density. — The  density 
of  a  body  depends  both  upon  its  mass  and  its  volume. 
If  we  were  to  select  some  one  substance  as  a  standard 
and  compare  the  density  of  every  other  substance  to  that 
standard,  we  should  obtain  a  set  of  results  called  the  rela- 
tive densities  of  substances.     The  most  suitable  standard 
is  water,  therefore  it  is  used  for  the  purposes  of  determining 
the  density  or  specific  gravity  of  solids  and  liquids.     The 
density  of  water  being  1,  the  weight  of  any  solid  or  liquid 
can  be  readily  found  if  the  specific  gravity  of  the  solid 
or  liquid  be  known. 

EXAMPLE. — If  the  specific  gravity  of  anthracite  coal  is 
1.4,  what  is  its  weight  per  cubic  foot? 

Solution. — As  the  relative  densities  of  water  and  coal 
are  as  1  :  1.4,  meaning  that  the  coal  is  1.4  times  the  weight 
of  water,  therefore,  as  water  weighs  62.5  Ibs.  per  cu.ft., 
a  cubic  foot  of  the  coal  will  weigh  62.5X1.4  =  87.5  Ibs. 

28.  How  to  Find  the  Specific  Gravity. — As  the  density 


LIQUIDS  AND  LIQUID  PRESSURE  21 

of  water  varies  with  its  temperature  as  well  as  with  its 
purity,  the  temperature  4°  C.  or  39°  F.  is  taken  for  the 
standard  density  because  the  density  of  water  is  greatest 
at  that  temperature.  In  order  to  get  the  most  accurate 
results,  distilled  water  at  the  temperature  given  must  be 
used. 

DEMONSTRATION.  —  Weigh  a  piece  of  coal  in  the  air 
and  note  its  weight;  weigh  again,  letting  the  coal  hang 
in  a  vessel  of  water,  and  the  scale  will  be  found  to  read 
less.  The  operation  may  be  expressed  by  the  following 
formula: 

~         _  _  Weight  of  the  body  in  air  _ 
Difference  of  the  weight  in  water  and  air' 
or 


In  this  example  W  is  the  weight  of  the  body  in  air,  W" 
its  apparent  weight  in  water. 

EXAMPLE.  —  A  piece  of  coal  weighs  48  ozs.  in  the  air 
and  weighs  9  ozs.  in  water,  what  is  its  specific  gravity? 

Solution.  —  4o     Q  =  1.23  sp.gr. 

29.  How  to  Find  the  Specific  Gravity  of  Bodies  Lighter 
than  Water.  —  If  the  body  be  lighter  than  an  equal  body 
of  water  and  will  not  sink,  it  must  be  fastened  to  a  heavy 
body  in  order  to  submerge  it.  The  specific  gravity  can 
then  be  found  as  follows: 

Weigh  the  body  in  air  (W),  then  weigh  a  heavy  sinker 
in  water  and  call  its  apparent  weight  S.  Tie  the  sinker 
to  the  body  and  weigh  them  both  in  water.  Call  the 
apparent  weight  W".  Compute  the  specific  gravity  from 
the  formula 

W 


22  MINING  AND  MINE  VENTILATION 

LAW  OF  FLOATING  BODIES. — A  floating  body  displaces 
a  volume  of  liquid  that  has  the  same  weight  as  the  floating 
body. 

EXAMPLE. — A  piece  of  wood  weighs  4  ozs.  in  air  (W), 
a  sinker  registers  5  ozs.  in  water  (S),  and  the  two  when 
tied  together  and  submerged  register  3  ozs.  (W").  It  is 
noticed  that  the  wood  not  only  displaces  its  own  weight 
of  water,  but  buoys  up  2  ozs.  of  the  weight  of  the  sinker; 
therefore  the  wood  displaces  4+2  ozs.  of  water,  hence 
its  specific  gravity  is 

4  4 

=  |=.67. 


4+(5-3)     6 

30.  How  to  Find  the  Specific  Gravity  of  Liquids. — The 
specific  gravity  is  accurately  obtained  by  means  of  the 
specific  gravity  bottle.  Any  bottle  with  a  small  neck 
having  a  fixed  mark  around  it  can  be  used.  First,  weigh 
the  bottle  when  empty  (a);  then  fill  with  water  to  the 
fixed  mark  and  weigh  (6).  The  difference  will  be  the 
weight  of  the  water  (b  —  a).  Fill  the  bottle  with  the 
liquid  of  which  the  specific  gravity  is  required  and  weigh 
(c) ;  the  difference  (c— a)  gives  the  weight  of  the  same  volume 
of  the  liquid;  then  the  specific  gravity  will  be 

Weight  of  liquid _c— a 

Weight  of  equal  volume  of  water    6  — a' 

EXAMPLE. 

Grammes 

Bottle+water 65 

Bottle 15 

Weight  of  water 50 

Bottle + calcium  chloride  solution 75 

Bottle 15 

Weight  of  solution 60 


LIQUIDS  AND  LIQUID  PRESSURE 


23 


Therefore  the  specific  gravity  or  relative  density  of  the 
calcium    chloride    solution  =  f$  =  1.2    (taking 
water  as  1) . 

For  practical  purposes  this  method  would 
be  slow  and  tedious,  and  in  such  cases  the 
hydrometer  is  employed.  This  instrument 
(Fig.  4)  consists  of  a  bulb  attached  to  a 
long  stem  and  is  weighted  at  the  bottom 
with  mercury  or  small  lead  shot  so  that  it 
will  float  upright  in  liquid.  The  stem  is 
graduated,  usually  with  a  paper  scale  inside 
the  glass.  The  reading  on  the  stem  corre- 
sponding to  the  level  of  the  liquid  in  which 
the  hydrometer  is  inserted  can  be  easily 
read. 

The  densities  and  specific  gravities  in  table 
A  are  averages  of  results  found  by  different 
observers. 


FIG.  4. 


QUESTIONS 


1.  Why  do  liquids  buoy  up  objects  immersed  in  them? 

2.  State  the  law  of  floating  bodies. 

3.  A  certain  bottle  when  filled  with  water  weighs  156 
gms.;    when  filled  with  an  oil  it  weighs  148  gms.     If  the 
empty  bottle  weighs  73  gms.  find  the  specific  gravity  of 
the  oil. 

4.  A  boat  displaces  580  cu.ft.  of  water;   find  the  weight 
of  the  boat. 

5.  A  tank  5  ft.  deep  and  10  ft.  square  is  filled  with 
water.     What  is  the  pressure  on  the  bottom  of  the  tank? 
What  on  one  side? 

6.  How  high  must  the  reservoir  of  a  city's  water  sys- 
tem be  above  any  point  to  produce  a  pressure  of  50  Ibs. 
per  square  inch  at  that  point? 


24 


MINING  AND  MINE  VENTILATION 


TABLE  A 


Density  Sp.gr. 

Density  in  Lbs. 
per  Cu.ft. 

Coal,  anthracite  (varies)  
Charcoal  (oak)  

1.5 
0.57 

93.75 
35  6 

Ice   

0  917 

57  3 

Sandstone  

2  35 

146  8 

Aluminum. 

2  57 

160  6 

Glass  

2  60 

162  5 

Quartz 

2  65 

165  6 

IMarble 

2  65 

165  6 

Granite 

2  75 

171  8 

Iron  (gray  cast)  . 

7  08 

442  5 

Zinc  (cast) 

7  10 

443  7 

Tin  (cast) 

7  29 

455  6 

Iron  (wrought)  

7.85 

490  6 

Brass  (yellow)  

8.44 

527.5 

Brass  (red)    

8  60 

537  5 

Nickel  

8.60 

537.5 

Copper  (cast) 

8  88 

555  0 

Silver  (cast)  
Lead  (cast) 

10.45 
11  34 

653.1 

708  7 

Mercury  

13.6 

850.0 

Gold 

19  3 

1206  2 

Platinum.        .... 

21.45 

1340  .  6 

Water  (pure  39°  F.)  

1.00 

62.5 

7.  What  is  the  vertical  depth  of  a  column  of  water 
which  counterbalances  a  column  of  mercury  30  ins.  deep 
when  the  liquids  are  placed  in  the  U-tube? 

8.  Why  does  a  hydrometer  float  vertically  in  a  liquid? 

9.  A  boy  can  lift  75  Ibs.     How  many  cubic  inches  of 
coal,  the  sp.gr.  of  which  is  1.4,  can  he  lift? 

10.  A  block  of  wood  is  1  ft.  square  and  2  ft.  long.     Its 
sp.gr.  is  .65.     How  much  pressure  would  be  required  to 
keep  it  under  water? 

11.  How  do  you  find  the  specific  gravity  of  a  liquid? 

12.  How  do  you  find  the  specific  gravity  of  a  solid 
which  is  lighter  than  water? 


LIQUIDS  AND  LIQUID  PRESSURE  25 

13.  Which  offers  the  greater  resistance  to  compression, 
liquids  or  gases? 

14.  If  a  cubic  foot  of  anthracite  coal  weighs  90  Ibs. 
what  is  its  specific  gravity? 

15.  A  cubic  foot  of  sandstone  (sp.gr.  2.35)  is  suspended 
in  water  by  a  rope.     What  is  the  tension  on  the  rope? 
What  will  it  be  when  it  is  lifted  from  the  water?* 

16.  A  shaft  mine  500  feet  deep  is  allowed  to  fill  with 
water.     A  certain  section  of  the  mine  was  squeezing  prior 
to  the  water  entering.     To  what  extent  will  the  water  aid 
in  stopping  the  squeeze? 

17.  If  a  piece  of  anthracite  coal  weighs  50  ozs.  in  the 
air  and  its  apparent  weight  in  water  is  15  ozs.,  what  is  the 
specific  gravity  of  the  coal,  and  what  is  its  weight  per  cubic 
foot? 

18.  If  a  body  lighter  than  water  weighs  15  ozs.  in  the 
air  and  a  sinker  weighs  25  ozs.  in  water  and  the  body  and 
the  sinker  fastened  together  weigh  20  ozs.  in  water,  what 
is  the  specific  gravity  of  the  body? 

19.  If  the  weight  of  a   certain   liquid   is  10  ozs.   and 
the  weight  of  an  equal  volume  of  water  is  12  ozs.,  what 
is  the  specific  gravity  of  the  liquid? 

20.  An  engineer  reporting  on  a  certain  tract  of  coal 
land  discovered  that  180  acres  contained  coal,  the  seam 
being  flat  and  7  feet  thick  throughout  the  entire  property. 
How  many  tons  of  coal  are  on  this  property  if  the  specific 
gravity  of  the  coal  is  1.4? 

21.  A  block  of  wood  1  ft.  square  and  2  ft.  long  is  pushed 
down  into  water  until  its  upper  side  is  6  ins.  below  the 
surface.     What  is  the  upward  pressure  upon  the  bottom 
of  the  block?      What   is   the   downward   pressure    of  the 
water  on  the  top  of  the  block?     How  much  pressure  is 
required  to  keep  the  block  in  place  if  its  specific  gravity  is 
.65?     How  much  pressure  would  be  required  to  keep  it 


26  MINING  AND  MINE  VENTILATION 

at  a  depth  of  2  ft.?    Ans.  187.5  Ibs.,  62.5  Ibs.,  43.75  Ibs., 

43.75  Ibs. 

22.  A  cake  of  ice  6  ft.  square  and  2  ft.  thick  is  floating 
on  a  lake.  How  much  will  it  settle  in  the  water  if  a  man 
weighing  180  Ibs.  stands  upon  it?  Ans.  .96  inch. 


CHAPTER  V 
HEAT 

THE  commonly  used  unit  to  measure  the  quantity  of 
heat  generated  by  the  burning  of  coal  or  other  substance 
is  called  the  British  Thermal  Unit  (B.T.U.).  It  is  equiv- 
alent to  the  amount  of  heat  required  to  raise  the  temper- 
ature of  1  Ib.  of  water  1  degree  of  the  Fahrenheit  scale,  or 
1  B.T.U.  is  equivalent  to  778  foot-pounds. 

When  heat  is  added  to  a  body,  whether  solid,  liquid 
or  gaseous,  the  vibration  of  the  molecules  composing  the 
body  increases.  This  increased  molecular  motion  will 
require  an  increased  space  between  the  molecules,  and 
the  body  grows  larger  in  volume — that  is,  it  expands — 
and  cooling  a  body  will  diminish  its  molecular  motion  and 
reduce  its  volume.  The  vibratory  movement  will  cease 
only  when  a  body  is  deprived  of  all  its  heat. 

Changes  in  temperature  are  detected  and  measured 
by  the  thermometer.  To  determine  the  actual  amount 
of  change  in  temperature  in  any  case  and  to  make  it 
possible  to  compare  the  records  of  one  thermometer  with 
those  of  another,  the  thermometers  must  be  similarly  con- 
structed. To  do  this  we  must  have  one  or  more  easily 
determined  temperatures,  called  the  FIXED  POINTS.  (1) 
Careful  experimenting  has  shown  that  the  temperature 
at  which  pure  ice  melts  is  practically  constant,  and  (2) 
that  the  temperature  of  steam  as  it  comes  from  boiling 
water  is  likewise  constant  when  the  pressure  upon  the 
water  is  constant.  Then  to  establish  the  fixed  points 
the  bulb  and  part  of  the  stem  of  the  thermometer  are  filled 
with  mercury  and  are  placed  in  a  vessel  containing  finely 

27 


28  MINING  AND  MINE  VENTILATION 

broken  ice  and  allowed  to  remain  until  there  is  no  further 
change  in  the  final  position  of  the  top  of  the  mercury. 
The  top  of  the  mercury  is  then  marked;  this  point  is 
called  the  freezing-point  of  water  or  the  melting-point  of 
ice.  The  thermometer  is  then  put  into  a  steam  generator 
and  left  until  the  mercury  ceases  to  expand;  this  point  is 
then  marked  and  is  called  the  boiling-point.  On  the  Fahren- 
heit thermometer  the  freezing  point  of  water  is  marked 
32  degrees  and  the  boiling-point  212  degrees.  On  this 
scale  the  difference  between  the  two  fixed  temperatures 
is  divided  into  180  degrees. 

The  centigrade  scale  differs  from  the  Fahrenheit  in 
making  the  freezing-point  0°  and  the  boiling-point  100°, 
the  space  between  being  divided  into  100  equal  parts.  This 
thermometer  is  the  one  in  general  use  among  scientific  men. 

Water  boils  when  its  vapor  escapes  with  sufficient 
pressure  to  overcome  the  pressure  of  the  atmosphere  upon 
its  surface.  Hence  the  boiling-point  depends  upon  the 
pressure  of  the  atmosphere  or  the  vapor  within  a  vessel 
such  as  a  steam  boiler.  The  boiling-point  is  lower  as  the 
pressure  is  decreased  and  higher  as  the  pressure  is  increased. 
Warm  water  will  boil  under  the  receiver  of  an  air  pump 
or  on  top  of  a  high  mountain,  the  decreased  pressure  allow- 
ing the  free  movement  of  the  molecules.  At  a  point  in 
South  America,  9350  ft.  above  sea  level,  water  boils  at  such 
a  low  temperature  that  it  is  not  hot  enough  to  cook  potatoes. 

31.  Exception  to  the  General  Rule  of  Expansion. — 
Generally  speaking  water  expands  and  contracts  in  the 
manner  common  to  all  liquids,  but  between  the  tempera- 
tures (32°  and  39°  IT.)  it  presents  a  remarkable  and  most 
important  exception.  If  water  at  the  freezing-point  is 
warmed  its  volume  steadily  decreases  until  39°  F.  is  reached, 
but  when  it  is  further  heated  water  expands  as  other  liquids 
do,  up  to  its  boiling-point. 


HEAT  29 

Conversion  of  thermometer  readings  from  one  scale 
to  another: 

C.°  to  F.°,  multiply  by  9,  divide  by  5,  add  32. 

F.°  to  C.°,  subtract  32,  multiply  by  5,  divide  by  9. 

EXAMPLE.  —  Convert  350°  C.  into  the  corresponding 
Fahrenheit  reading. 


Solution.-F.0  =  +32  *  662°. 

o 

EXAMPLE.  —  Convert    662°    F.    into    the    corresponding 
centigrade  reading. 


. 

The  temperature  of  a  melting  solid  remains  unchanged 
from  the  time  melting  begins  until  the  body  is  entirely 
melted. 

TABLE  B 
TABLE   OF   AVERAGE   MELTING-POINTS 


Ice                             .      . 

0° 

C 

or 

32  00°  F. 

Sulphur  

..  .   115.1° 

C 

or 

239.18°  F. 

Lead. 

326 

c 

or 

618  8      F 

Silver   

.  .  950 

C 

or 

1742          F. 

Copper.  . 

.  .  .1100 

c 

or 

2012          F. 

Iron 

1500 

c 

or 

2732          F. 

Platinum  
Cast  iron  (gray)  
Steel.  . 

.  .  .  1900 
.  .  .  1275 
.  .1375 

c. 
c. 
c. 

or 
or 
or 

3452          F. 
2327         F. 
2507          F. 

TABLE  C 
APPROXIMATE   TEMPERATURES 

Just  glowing  in  the  dark,  about.     525°  C.  or  977°  F. 

Dark  red  ....................     700    C.  or  1292  F. 

Cherry  red  ...................     910    C.  or  1670  F. 

Bright  cherry  red  .............   1000    C.  or  1832  F. 

Orange  ......................   1160    C.  or  2120  F. 

White  .......................   1300    C.  or  2372  F. 

Dazzling  bluish  white  .........   1500    C.  or  2732  F. 

Bunsen  flame  ................    1500    C.  or  2732  F. 

Electric  arc  .  .                               .   3500    C.  or  6332  F. 


30  MINING  AND  MINE  VENTILATION 

32.  A  freezing  mixture  can  be  made  by  mixing  1  part 
of  salt  with  3  parts  of  snow  or  cracked  ice.  The  ice  in 
contact  with  the  salt  is  melted,  the  heat  necessary  for  the 
melting  being  withdrawn  from  the  objects  near  by.  The 
salt  is  dissolved  and  the  temperature  falls  to  the  freezing- 
point  of  the  salt  solution,  which  is  lower  than  that  of  water. 
In  this  manner  substances  are  frozen,  for  example  ice 
cream. 

QUESTIONS 

1.  What  effect  (a)   does  expansion  always  have  upon 
the  density  of  a  body?     (6)  Contraction?     (c)  Name  an 
important  exception   to   the   general   rule   that  expansion 
accompanies  a  rise  in  temperature. 

2.  What  are  the  fixed  points  (a)  on  a  Fahrenheit  ther- 
mometer?    (6)  On    a    centigrade    thermometer?     (c)  How 
are  they  marked? 

3.  Why  does  ice  float  in  water? 

4.  Is  boiling  water  over  a  gas  flame  receiving  any  heat? 

5.  If  the  bulb  of  a  thermometer  be  plunged  into  hot 
water  the  mercury  at  first  falls;  why? 

6.  How  is  it  possible  to  heat  water  above  the  ordinary 
boiling-point? 

7.  Convert  (a)  0°  C.  into  the  corresponding  Fahrenheit 
reading;     (b)    212°   F.   into   the   corresponding   centigrade 
reading. 

8.  From  the  time  a  piece  of  cast  iron  starts  to  melt 
until  it  is  all  melted  does  the  temperature  change? 

9.  Do   water   pipes   burst   when   they  freeze   or   when 
they  are  thawed? 

10.  Explain  why  water  boils  at  a  lower  temperature 
under  reduced  pressure. 

11.  A  piece  of  ice  is  floating  for  a  time  in  warm  water. 
Does   the  water  lose   heat?     Does   the  ice   receive   heat? 


HEAT  31 

Does   the   temperature   of  the   water   change?     Does   the 
temperature  of  the  ice  change? 

12.  What  is  the  temperature  of  the  Bunsen  flame? 

13.  When  a  body  expands  due  to  a  rise  in  temperature, 
do  the  molecules  increase  in  size? 

14.  Why  will  water  boil  at  a  lower  temperature  on  a 
high  mountain  than  at  sea  level? 

15.  When  will  the  vibratory  movement  of  the  mole- 
cules of  which  a  body  is  composed  cease? 

16.  At  what  temperature  is  water  at  its  greatest  den- 
sity? 

17.  Explain  why  the  specific  gravity  of  ice  is  less  than 
water. 

18.  Convert  (a)  32°  F.  into  the  corresponding  centi- 
grade reading;    (6)  60°  C.  into  the  corresponding  Fahren- 
heit reading. 

19.  Seventy-six  degrees  is  called  summer  temperature 
on  the  Fahrenheit  thermometer.     What  will  be  its  reading 
on  the  centigrade  thermometer? 


CHAPTER   VI 
GASES 

33.  The  Atmosphere. — The  earth  is  surrounded  by  a 
great  mass  of  gas  commonly  known  as  the  ATMOSPHERE 
or  ATR.     The  estimated  height  to  which  the  atmosphere 
extends   has    not   been   definitely    fixed,    but    observation 
on  meteors  show  that  it  really  extends  to  a  height  of  at 
least  100  miles,  and  indeed  at  that  height  it  is  sufficiently 
dense  to  cause  the  rapid  combustion  of  a  meteor  passing 
through  it.     This  great  volume  of  gas  rests  upon  the  earth. 
The  weight  of  the  whole  mass  is  such  that  it  presses  on 
every  square  inch  of  the  earth's  surface  at  sea  level  with 
a  weight  equal  to  14.7  Ibs.     At  higher  elevations  the  pres- 
sure is  not  so  great.     The  pressure  of  the  entire  mass  of 
the  whole    atmosphere   may   be  approximately  found  by 
multiplying  14.7  by  the  number  of  square  inches  on  the 
whole  surface  of  the  earth.     In  round  numbers  we  might 
say  that  it  is  five  thousand  million  of  millions  of  tons. 

34.  Composition  of  the  Atmosphere. — Pure  dry  air  is 
chiefly  a  mixture  of  oxygen,  nitrogen  and  carbon  dioxide, 
containing  nearly  four  volumes   or  parts   of  nitrogen  to 
one  part  of  oxygen.     Figures  that  are  still  more  exact, 
and  which  are  frequently  used  by  the  chemist  when  cal- 
culating the  amount  of  oxygen  in  a  given  volume  of  air, 
are  as  follows: 

Per  Cent. 

Carbon  dioxide  (CO2) 0.03 

Oxygen  (O2) 20.93 

Nitrogen  (N2) 79.04 

32 


GASES  33 

These  percentages  are  those  commonly  used  and  refer 
to  parts  by  volume — that  is,  100  cubic  feet  of  air  contain 
0.03  cu.ft.  of  carbon  dioxide,  20.93  cu.ft.  of  oxygen  and 
79.04  cu.ft.  of  nitrogen.  By  weight  the  percentages  of 
oxygen  and  nitrogen  are  different,  for  in  100  Ibs.  of  dry 
air  there  are  approximately  23  Ibs.  of  oxygen  and  77  Ibs. 
of  nitrogen.  Ordinary  air  is  not  perfectly  dry,  but  con- 
tains some  water  vapor. 

Besides  oxygen,  nitrogen  and  carbon  dioxide,  air  con- 
tains five  so-called  rare  gases  which  contribute  about  1 
per  cent  of  the  total  volume.  These  gases  are  about  the 
same  as  nitrogen  and  are  considered  as  nitrogen  in  most 
calculations. 

All  of  the  gases  found  in  pure  air  are  without  color, 
smell  or  taste.  Pure  dry  air  contains  oxygen  and  nitro- 
gen in  the  same  proportions  by  volume  all  over  the  globe, 
at  either  sea  level  or  high  altitudes. 

35.  Atoms  and  Molecules. — We  often  speak  of  atoms 
as  if  an  atom  of  matter  could  exist.  We  do  so  simply 
because  such  an  expression  helps  to  describe  and  interpret 
chemical  action.  Atoms  do  not  as  a  rule  exist  in  the  un- 
combined  state.  As  soon  as  atoms  are  freed  from  combina- 
tion they  at  once  unite  with  some  other  atom  or  atoms. 
When  atoms  unite  the  combination  is  called  a  MOLECULE. 
Hence  a  molecule  is  formed  by  the  chemical  union  of  two 
or  more  atoms.  The  atoms  forming  a  molecule  may  be 
like  or  unlike.  If  the  atoms  in  a  molecule  are  atoms  of 
the  same  element  or  kind,  then  the  molecule  is  a  mole- 
cule of  an  element;  but  if  the  atoms  of  different  elements 
are  combined,  then  the  molecule  is  the  molecule  of  a  com- 
pound. All  matter  consists  of  molecules  and  the  mole- 
cules are  made  up  of  atoms.  We  may  define  an  ATOM  as 
the  smallest  conceivable  division  of  an  element,  and  a 
MOLECULE  as  the  smallest  part  of  a  compound,  or  of  an 


34 


MINING  AND  MINE  VENTILATION 


element  which  can  exist  in  a  free  state  and  manifest  the 
properties  of  the  compound.  Thus  the  smallest  particle 
of  marsh  gas  that  can  exist  is  a  molecule  of  marsh  gas,  but  a 
molecule  of  marsh  gas  contains  smaller  particles  still,  viz., 
atoms  of  carbon  and  hydrogen. 

36.  Elements. — An  elementary  body  consists  of  a  simple 
substance  which  cannot  be  analyzed  or  reduced  to  parts 
that  have  properties  other  than  those  peculiar  to  itself. 
An  element  is  a  substance  composed  wholly  of  like  atoms; 
oxygen,  nitrogen,  hydrogen,  gold,  silver,  iron,  etc.,  are  all 
elements  neither  of  which  can  be  divided  chemically  into 
two  or  more  substances;  other  substances  can  be  added 
to  them,  but  we  cannot  get  simpler  substances  from  them. 

TABLE  D 
TABLE  OF  THE   MOST  IMPORTANT  ELEMENTS 


Name. 

Symbol. 

Approximate 
Atomic  Weight. 

Oxygen  

o 

16 

Nitrogen 

N 

14 

Hydrogen  

H 

1 

Carbon 

c 

12 

Sulphur   

s 

32 

Iron 

Fe 

56 

Lead.                          

Pb 

207 

Gold  

Au 

197 

Copper.                          

Cu 

63  5 

Chlorine  

Cl 

35.4 

Calcium. 

Ca 

40 

Aluminium  

Al 

27 

Mercury 

He 

200 

Nickel      

Ni 

58 

Rhodium 

Rh 

103 

Silver     

Ag 

108 

Sodium 

Na 

23 

Tin.  .            

Sn 

119 

Tungsten 

W 

184 

Zinc      .              

Zn 

65 

GASES  35 

37.  Density. — Density  is  compactness  of  mass  and  has 
reference  to  the   amount   of  matter  in   a  given  volume. 
When  the  density  of  a  gas  is  spoken  of  it  is  understood  to 
be  compared  with  hydrogen  gas  as  a  standard  taken  as  1. 
Thus  the  density  of  air  is  14.4  and  of  oxygen  16.0.     That 
is,  air  and  oxygen  are  respectively  14.4  and  16  times  as 
heavy  as  hydrogen. 

38.  Specific  Gravity. — When  the  specific  gravity  of  a 
gas  is  mentioned  it  is  understood  that  the  comparison  is 
made  with  air  as  a  standard.     Thus  the  specific  gravity 
of  carbon  dioxide  is  1.527  and  marsh  gas  0.555,  one  being 
approximately  1J  times  as  heavy,  and  the  other  half  as 
heavy  as  air,  the  specific  gravity  of  air  being  1.     Specific 
gravity  is  tbe  measure  of  the  density  of  a  body. 

The  density  or  specific  gravity  of  all  gases  is  affected 
by  the  temperature  and  pressure;  if  the  temperature  be 
increased  the  density  is  reduced  and  if  the  temperature 
be  decreased  the  density  is  increased.  The  pressure  also 
affects  the  volume  and  therefore  the  weight,  if  the  gas  be 
free  to  expand  or  contract.  Hence  the  comparison  of  all 
densities  and  specific  gravities  is  understood  to  have  been 
made  at  the  same  standard  temperature  and  pressure, 
namely,  60°  F.  and  30"  barometer. 

The  units  of  measure  are  as  follows: 

For  solids  and  liquids,  as  has  been  stated,  62.5  Ibs., 
the  weight  of  1  cu.ft.  of  water.  For  gases,  .0766,  the  weight 
of  1  cu.ft.  of  air  (temperature  60°  F.,  barometer,  30"). 

EXAMPLE. — If  the  specific  gravity  of  carbon  dioxide  is 
1.527,  what  is  the  weight  of  a  cubic  foot  of  the  gas? 

Solution.— 1.527  X.  0766  =  .1169. 

EXAMPLE. — Find  the  weight  of  5  cu.ft.  of  marsh  gas 
at  a  temperature  of  60°  F.  and  a  pressure  due  to  30  ins. 
of  barometer,  the  gas  having  a  specific  gravity  of  0.559. 

Solution.— 0.559  X  .0766  X  5  =  .2141. 


36 


MINING  AND  MINE  VENTILATION 


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GASES  37 

RULE  1. — To  find  the  specific  gravity  of  a  solid  or 
liquid  divide  its  weight  per  cubic  foot  by  the  weight  of 
a  cubic  foot  of  water  (62.5  Ibs.). 

RULE  2. — To  find  the  weight  per  cubic  foot  of  a  solid 
or  liquid  multiply  its  specific  gravity  by  the  weight  of  a 
cubic  foot  of  water  (62.5  Ibs.). 

In  Table  E  is  shown  a  comparison  of  several  gases,  most 
of  which  are  met  with  in  mines,  all  of  which  the  student 
should  commit  to  memory: 

RULES 

To  FIND  THE  SPECIFIC  GRAVITY  OF  A  GAS 

0  atomic  weight 

~UA~ 

~         _  weight  per  cubic  foot  of  a  gas 
weight  per  cubic  foot  of  air 

To  FIND  THE  WEIGHT  PER  CUBIC  FOOT  OF  A  GAS 

1.  Weight  per  cubic  foot  =  atomic  weigh tX. 005645. 

2.  Weight  per  cubic  foot  =  sp.gr.  X weight  of  cu.ft.  of  air. 
It  should  be  noticed  that  the  weight  of  solids  bears  no 

relation  to  the  atomic  weight;  the  reason  for  this  is,  that 
like  volumes  of  solids  or  liquids  do  not  necessarily  contain 
the  same  number  of  molecules.  A  solid  may  have  an  atomic 
weight  of  5  and  yet  weigh  more  per  cubic  foot  than  another 
solid  having  an  atomic  weight  of  6. 

QUESTIONS 

1.  If  the  specific  gravity  of  a  gas  is  known,  how  do  you 
find  the  weight  per  cubic  foot? 

2.  Why  do  you  not  feel  the  pressure  of  the  atmosphere? 

3.  What  is  the  difference  between  an  atom  and  a  mole- 
cule? 


38  MINING  AND  MINE  VENTILATION 

4.  What  is  an  element? 

5.  What  is  the  atomic  weight  of  hydrogen,  carbon,  nitro- 
gen, oxygen  and  sulphur? 

6.  If  the  specific  gravity  of  carbon  dioxide  is   1.527, 
what  does  it  weigh  per  cubic  foot? 

7.  What  is  the  weight  of  a  cubic  foot  of  oxygen? 

8.  What  is  the  specific  gravity  of  ethane  and  what  is 
its  weight  per  cubic  foot? 

9.  If  the  specific  gravity  of  coal  is  1.45,  what  is  the 
weight  of  100  cu.ft.  of  coal? 

10.  Which    is    the    more    dense,  marsh    gas  or  carbon 
dioxide? 

11.  If  a  cubic  foot  of  sandstone  weighs  180  Ibs.,  what 
is  its  specific  gravity? 

12.  What  is  fire  damp? 

13.  Will  marsh  gas  or  methane  explode? 

14.  What  are  the  three  forms  of  matter? 

15.  What  are  the  properties  of  ethane  gas? 

16.  What  is  black  damp? 

17.  What  is  the  composition  of  air? 

18.  If  a  cubic  foot  of  hydrogen  weighs  .0056  lb.,  what 
is  the  weight  of  a  cubic  foot  of  carbon? 

19.  If  two  or  more  atoms  unite  what  is  the  combina- 
tion called? 

20.  What  is  meant  when  it  is  said  that  carbon  dioxide 
is  more  dense  than  marsh  gas? 

21.  Is  the  density  or  specific  gravity  of  a  gas  affected 
by  the  temperature  and  pressure? 

22.  If  the  weight  of  a  cubic  foot  of  coal  is  90  Ibs.,  what 
is  its  specific  gravity? 

23.  What  is  the  pressure  per  square  inch  due  to  the 
atmosphere  at  sea  level? 

24.  If  the  barometer  reading  is  28  inches,  what  is  the 
pressure  per  square  inch? 


CHAPTER   VII 

GASES 

39.  Chemical  Compounds. — In  chemical  compounds  the 
combining  atoms  unite  in  definite  fixed  proportions.     The 
elements  which  make  up  a  chemical  compound  are  called 
COMPONENTS.     Chemical   compounds   have   three   essential 
characteristics:     (1)    their   components   are    held   together 
by  chemical  attraction.     The  hydrogen  and  oxygen,  which 
are  the  components  of  water,  cannot  be  separated  unless 
their  attraction  for  each  other  is  overcome  by  heat  or  some 
other  agent.     (2)  In  any  given  chemical  the  components 
are  always  in  the  same  ratio.     Thus  pure  water  always 
contains  eight  parts   (by  weight)    of  oxygen  and   one  of 
hydrogen.     (3)  In    chemical    compounds    the    identity    of 
the  components  is  lost. 

40.  Mechanical  Mixtures. — The  molecules  of  the  dif- 
ferent  substances  forming  the  mixtures  may   be   present 
in  any  proportion.     Mixtures  must  not  be  confused  with 
chemical  compounds.     The  parts  of  a  mixture  may  vary  in 
nature  as  well  as  in  proportion;  they  are  also  held  together 
loosely  and  may  often  be  separated  by  some  mechanical 
operation,   as   filtering    or   sifting.     The   atmosphere   is   a 
good  example  of  mechanical  mixture.     The  proportion  of 
oxygen  and  of  nitrogen  is  not  fixed,  but  varies  between 
small  limits,  which  may  be  detected  by  accurate  analysis. 

41.  Chemical   Symbols. — To   facilitate   the   writing   of 
chemical  equations  the  elements  are  usually  denoted  by 
their   first   letter.     Thus   H   is   the   symbol   for   hydrogen, 
O  for  oxygen.     Since  several  elements  have  the  same  initial 

39 


40  MINING  AND  MINE  VENTILATION 

letter,  the  symbol  for  some  elements  contains  two  letters. 
Thus  C  is  the  symbol  for  carbon  while  the  symbol  for 
calcium  is  Ca.  It  should  be  remembered  that  the  symbols 
represent  single  atoms.  Thus  O  represents  one  atom  of 
oxygen;  C  represents  one  atom  of  carbon.  If  more  than 
one  atom  is  to  be  designated  the  required  number  is  placed 
before  the  symbol  as  follows: 

2C  means  2  atoms  of  carbon, 
4O  means  4  atoms  of  oxygen, 
3H  means  3  atoms  of  hydrogen. 

Chemical  compounds  are  expressed  by  a  combination 
of  symbols  representing  atoms,  thus : 

CH4  is  the  formula  for  marsh  gas,  meaning  that  the 
gas  is  composed  of  one  atom  of  carbon  and  four  of  hydrogen. 
If  we  wish  to  designate  several  molecules  the  proper  number 
is  placed  before  the  formula,  thus: 

2CH4  means  2  molecules  of  marsh  gas. 

A  group  of  symbols  designed  to  express  the  composition 
of  a  compound  is  called  a  CHEMICAL  FORMULA.  Thus 
H2O  is  the  formula  for  water,  similarly  CO2  is  the  for- 
mula for  carbon  dioxide. 

42.  Atomic  Weight. — Atomic  weight  means  RELATIVE 
WEIGHT  only;  it  does  not  mean  pounds  or  ounces  or  any 
other  denomination.  An  atom  of  hydrogen  is  taken  as 
a  standard.  Hydrogen  being  the  lightest  known  element 
in  nature,  1  is  therefore  adopted  as  its  atomic  weight. 
Thus  when  we  say  the  atomic  weight  of  oxygen  is  sixteen 
we  mean  that  an  atom  of  oxygen  weighs  16  times  as  much 
as  an  atom  of  hydrogen. 

Different  atomic  weights  are  sometimes  given  for  the 


GASES  41 

same  element.  This  is  due  to  the  disagreement  among 
chemists  as  to  the  accuracy  of  certain  results.  The  method 
of  finding  the  atomic  weight  is  explained  in  Chapter  VI. 

43.  Molecular  Weights. — The  molecular  weight  is  the 
sum  of  the  weights  of  the  atoms  in  a  molecule;    thus  a 
molecule  of  carbon  dioxide   (CO2),  contains  one  atom  of 
carbon  (the  atomic  weight  of  which  is  12),  and  two  atoms 
of  oxygen  (the  atomic  weight  of  oxygen  being  16).     There- 
fore its  molecular  weight  (of  C02)  is  12+(16X2)  =  44. 

When  the  formula  is  given  the  molecular  weight  of  any 
compound  can  be  found  by  adding  the  atomic  weights. 
Since  the  formula  of  a  compound  expresses  its  composi- 
tion, it  is  possible  to  calculate  the  percentage  composition 
of  weight.  The  formula  for  marsh  gas  is  CH4;  the  per- 
centage of  weight  of  each  element  composing  the  gas  is 
as  follows: 

1  atom  of  carbon  =  12 

4  atoms  of  hydrogen  (4X1)  =  4 

1  molecule  CH2  =  16 

It  is  readily  seen  that  the  carbon  forms  |J  or  f  or  75 
per  cent  by  weight  of  marsh  gas,  and  hydrogen  •&•  or  J  or 
25  per  cent  of  the  gas. 

EXAMPLE. — What  per  cent  of  the  weight  of  carbon 
dioxide  gas  is  oxygen? 

Solution. — Carbon  dioxide  (C02)  contains  1  atom  of 
carbon  and  2  atoms  of  oxygen.  The  molecular  weight  is 
therefore,  12 +  (16X2)  =44,  of  which  oxygen  forms  £f  or  ^ 
or  72T\  per  cent.  Ans. 

44.  Chemical  Equations. — Chemical    reactions  are  com- 
monly and  conveniently  represented  by  equations,  placing  the 
sum  of  the  factors  equal  to  the  sum  of  the  products.     Since 
matter  may  be  changed  in  its  form  but  cannot  be  destroyed, 


42  MINING  AND  MINE  VENTILATION 

the  individual  atoms  of  the  factors  reappear  in  the  prod- 
ucts; they  are  differently  arranged,  but  not  one  is  gained 
or  lost. 

Thus  when  quicklime  (CaO)  is  slaked  with  water  (H^O) 
the  following  equation  denotes  the  chemical  action  : 

CaO+H2O  =  Cao,H2O, 

that  is,  Ca(HO)2  or  Ca2HO,  from  which  we  learn  that 
40+16  =  56  parts  by  weight  of  calcium  oxide  combines 
with  2+16  =  18  parts  by  weight  of  water  to  form  56+18 
parts  by  weight  of  calcium  hydrate  (slaked  lime). 

Again,  when  methane  or  fire  damp  burns,  the  chemical 
reaction  is  represented  by  the  equation: 


1  vol.  +2  vols.  =  l  vol.  +2  vols., 
or 

1  cu.ft.+2  cu.ft.  =  l  cu.ft.+2  cu.ft., 

which  means  that  1  volume  of  fire  damp  requires  2  volumes 
of  oxygen  for  its  complete  and  exact  combustion  and  that 
the  fire  damp  forms  its  own  volume  of  carbon  dioxide 
and  2  volumes  of  water  in  the  form  of  steam. 

45.  Humidity  of  the  Air.  —  The  rate  at  which  water 
evaporates  or  "  objects  dry  "  when  exposed  to  the  air 
depends  upon  the  relative  humidity  of  the  air  at  the  time. 
For  example,  water  appears  on  the  surface  of  the  human 
body  as  perspiration.  When  the  relative  humidity  of  the 
air  is  low  the  evaporation  of  the  perspiration  is  rapid  and 
the  cooling  effect  is  sufficient  for  the  needs  of  the  body; 
but  when  the  relative  humidity  is  high,  say  80  to  100  per 
cent,  the  perspiration  may  come  freely,  but  on  account 
of  the  slow  evaporation  the  cooling  effect  is  small  and 


GASES 


43 


we  suffer  from  the  excess  of  heat.  Hence  the  high  relative 
humidity  of  air  in  a  mine  renders  it  oppressive. 

During  the  warm  weather  the  liability  of  a  dust  explo- 
sion in  bituminous  mines  is 
not  as  great  as  in  the  winter 
time.  This  is  due  to  the  fact 
that  the  warm  well-saturated 
air  entering  the  mines  in  the 
summer  time  is  lowered  in 
temperature,  and  thereby 
contracts,  reducing  the  moist- 
ure-holding capacity  of  the 
air,  by  reason  of  which  con- 
traction the  moisture  in  the 
air  is  distributed  along  the 
passage-ways  and  saturates 
the  coal  dust.  The  higher 
the  temperature  of  the  air 
the  more  water  it  will  absorb. 
(See  Table  F.) 

The  humidity  of  the  mine 
air  also  affects  the  limits  at 
which  marsh  gas  and  air  will 
explode.  A  mixture  of  marsh 
gas  and  air  that  would  just 
explode  when  the  air  is  un- 
dersaturated  would  be  inex- 
plosive  in  air  saturated  with 
watery  vapor.  Fic.r5. 

46.  The  Hygrometer  and 

Its  Use. — The  hygrometer  is  an  instrument  used  for  de- 
termining the  amount  of  watery  vapor  in  the  air;  or  in 
other  words  the  relative  humidity  of  the  air. 

The   hygrometer  is   shown   in   Fig.    5.     It   consists   of 


44 


MINING  AND  MINE  VENTILATION 


two  thermometers  placed  side  by  side,  the  one  a  dry  and 
the  other  a  wet-bulb.  Round  the  wet-bulb  is  fastened  an 
absorbent  wick  the  end  of  which  dips  in  a  vessel  of  water. 
This  keeps  the  bulb  wet  and  the  rate  of  evaporation  affects 
the  temperature  of  the  bulb.  If  there  is  little  moisture 
in  the  air  the  evaporation  takes  place  rapidly  and  the 
wet-bulb  thermometer  will  read  considerably  lower  than 
the  other.  The  more  vapor  present  in  the  air  the  more 
slowly  the  water  evaporates  from  the  bulb,  and  consequently 
the  LESS  the  cooling  effect  upon  it. 

Evaporation  is  always  accompanied  by  loss  of  heat. 
It  is  evident  then  that  the  GREATER  the  difference  between 
the  readings  of  the  two  thermometers  the  LESS  moisture 
is  present  in  the  air  of  the  mine. 

TABLE  F 

THE  WEIGHT  OF   WATER  VAPOR  CONTAINED   IN 
SATURATED  AIR 

Barometer  30  Inches 


Temp.  Deg.  F.        Grains  per  cu.ft. 

Temp.  Deg.  F. 

Grains  per  cu.ft. 

20 

1.321 

60 

5.745 

25 

1.611 

65 

6.782 

30 

1.956 

70 

7.980 

32 

2.113 

75 

9.356 

35 

2.366 

80 

10.934 

40 

2.849 

85 

12.736 

45 

3.414 

90 

14.790 

50 

4.076 

95 

17.124 

55 

4.849 

100 

19.766 

NOTE. —  437|  grains  =  1  Av.  oz. 
7000    grains  =  1  Av.  Ib. 

THE    WEIGHT    OF    AQUEOUS    VAPOR    (ABSOLUTE    HU- 
MIDITY).— The  weight  of  a  cubic  foot  of  aqueous  vapor 


GASES  45 

at   different   temperatures   and   percentages   of   saturation 
is  called  absolute  humidity. 

RELATIVE  HUMIDITY. — The  relative  humidity  depends 
on  the  temperature  of  the  air.  If  we  make  moist  air  cooler 
its  relative  humidity  will  increase  without  increasing  its 
absolute  ^humidity.  If  it  is  cooled  sufficiently  its  rela- 
tive humidity  will  become  100  per  cent,  which  is  satura- 
tion. 

DEW  POINT. — The  dew  point  is  that  temperature  of 
the  air  at  which  the  invisible  moisture  (in  the  air)  begins 
to  condense  into  visible  water  drops. 

Saturated  aqueous  vapor  is  but  little  more  than  half 
as  heavy  as  the  same  volume  of  dry  air  under  like  con- 
ditions of  temperature  and  pressure.  In  all  ordinary  com- 
putations it  is  assumed  that  the  expansion  and  contraction 
of  partially  saturated  aqueous  vapor  is  in  accordance  with 
the  same  laws  as  apply  to  air  and  ordinary  gases  which 
do  not  easily  condense  to  the  liquid  state. 

The  density  of  saturated  aqueous  vapor  is  not  deter- 
mined directly  from  experiment,  but  is  deduced  theoretically 
from  the  observed  fact  that  two  volumes  of  hydrogen  and 
one  of  oxygen  combine  to  produce  two  volumes  of  water 
vapor. 

The  weights  of  unit  volumes  of  hydrogen,  oxygen  and 
dry  air  are  accurately  known,  from  which  the  specific 
gravity  of  aqueous  vapor  is  found  to  be  0.6221. 

THE  PROPER  HUMIDITY.— "-Dr.  H.  M.  Smith,  M.D.,  in 
his  book  on  "  INDOOR  HUMIDITY,"  says:  "  It  was  most 
interesting  and  instructive  to  find  that  on  the  perfect  days 
in  May  and  early  June,  with  all  the  windows  open  admitting 
freely  the  outdoor  air,  a  thermometer  stood  at  65  to  68 
degrees  and  the  hygrometer  registered  about  60  per  cent 
relative  humidity. 

11  If  a  room  at  68  to  70  degrees  is  not  warm  enough  for 


46 


MINING  AND  MINE  VENTILATION 


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GASES  47 


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48  MINING  AND  MINE  VENTILATION 

any  healthy  person  it  is  because  the  humidity  is  too  low 
and  water  should  be  evaporated  to  bring  the  moisture  up 
to  the  right  degree.  In  other  words  water  instead  of  coal 
should  be  used  to  make  rooms  comfortable  when  the  tem- 
perature has  reached  68  degrees. 

"  Humidity  causes  the  temperature,  as  shown  by  the 
thermometer,  to  vary  as  much  as  35  degrees  from  the  tem- 
perature as  felt  by  your  body.  If  it  were  not  for  the 
moisture  in  the  air  it  would  be  too  cold  to  live  in.  The 
reason  for  this  is  that  if  the  air  is  dry  the  heat  goes  through 
it  without  warming  it.  If  the  air  is  moist  it  stops  the  ra- 
diated heat  and  warms  it  so  that  humidity  acts  as  a  check 
and  prevents  the  heat  from  passing  through  the  air.  The 
dry  air  allows  too  much  radiation  from  the  body  and  too 
rapid  evaporation  makes  us  feel  cold." 

The  cooling  effect  produced  by  a  wind  does  not  neces- 
sarily arise  from  the  wind  being  cooler,  for  it  may,  as 
shown  by  the  thermometer,  be  actually  warmer,  but  arises 
from  the  rapid  evaporation  it  causes  from  the  surface  of 
the  skin.  Without  moisture  in  the  air  there  would  be  no 
life.  The  lack  of  humidity  causes  discomfort,  ill  health, 
catarrhs,  colds  and  other  diseases  of  the  mucous  mem- 
brane. It  is  supposed  that  colds  are  taken  (in  winter) 
by  the  sudden  change  in  temperature  in  stepping  out  of 
doors,  but  as  a  matter  of  fact  the  change  in  humidity  is 
much  more  harmful.  In  buildings  heated  by  steam  and 
hot  water,  with  an  average  temperature  of  70  degrees,  the 
relative  humidity  averages  about  30  per  cent;  in  stepping 
from  this  atmosphere  to  an  outside  humidity  of  about  70 
per  cent  the  violent  change  is  productive  of  harm,  particu- 
larly to  the  delicate  mucous  membrane  of  the  air  pas- 
sages. The  pneumonia  period  is  the  season  of  artificial 
heat  in  living  rooms.  The  relative  humidity  should  never 
be  lower  than  60  to  65  per  cent. 


GASES  49 

By  the  use  of  the  following  table  the  relative  humidity 
of  the  air  can  be  determined  from  the  hygrometer  readings. 

How  TO  FIND  RELATIVE  HUMIDITY  BY  THE  TABLE 

Look  in  column  on  left  for  the  nearest  degree  to  the 
dry-bulb  reading,  then  go  horizontally  along  until  the 
column  is  reached,  on  the  top  of  which  is  the  difference 
between  the  dry  and  wet-bulb  thermometers,  in  which 
column  the  relative  humidity  will  be  found. 

EXAMPLE. — Dry-bulb  reading  is  62°;  the  wet-bulb 
53°;  the  difference  is  9.  Find  62°  in  column  on  left,  run 
the  eye  horizontally  along  the  column  on  top  of  page  until 
9  is  reached,  when  the  relative  humidity  will  be  found  to 
be  54  per  cent. 

47.  Diffusion  of  Gases. — Fill  two  jars  with  gas,  one 
with  carbon  dioxide  and  the  other  with  hydrogen,  and 
place  them  mouth  to  mouth,  the  jar  containing  the 
heavier  gas  (carbon  dioxide)  beneath  the  jar  contain- 
ing hydrogen;  while  in  this  position  it  would  appear  that 
the  lighter  gas  in  the  upper  jar  would  rest  on  the  heavier 
gas  in  the  lower  jar;  it  will  be  found,  however,  that  this 
is  not  the  case,  as  in  a  short  time  the  gases  will  intermix 
and  the  composition  of  the  gas  in  each  jar  will  be  the  same. 
Further,  these  gases  will  never  separate  again  into  a  heavy 
and  light  layer  as  they  were  before  mixing. 

All  gases  when  in  proximity  to  each  other  mix  or  spread 
one  into  the  other.  The  greater  the  difference  between 
the  densities  of  the  gases  the  quicker  they  mix. 

This  property  of  gases  mixing  will  account  for  the  fact 
that  carbon  dioxide  is  not  always  found  on  the  floor  of  a 
mine,  but  is  sometimes  well  diffused  in  the  atmosphere. 

If  two  liquids  which  do  not  act  chemically  upon  each 
other  be  mixed  and  allowed  to  stand,  it  will  be  found  after 
a  short  time  that  the  heavier  liquid  has  settled  to  the  bottom. 


50  MINING  AND  MINE  VENTILATION 

LAW  of  DIFFUSION  OF  GASES. — The  rate  of  diffusion 
of  gases  varies  inversely  as  the  square  roots  of  their  densi- 
ties. 

EXAMPLE. — The  density  of  hydrogen  being  1,  that 
of  carbon  dioxide  being  22,  their  relative  rates  of  diffusion 
will  be  inversely  as  Vl  :  \/22  which  is  as  1  :  4.69.  That 
is,  hydrogen  will  diffuse  4.69  times  as  quickly  into  carbon 
dioxide  as  carbon  dioxide  will  diffuse  into  hydrogen. 

EXAMPLE. — If  the  density  of  marsh  gas  is  8,  and  of 
air  14.4,  what  is  the  rate  of  diffusion?  Ans.  1  :  1.34. 

Thus  we  see  from  the  foregoing  examples  that  4.69 
volumes  of  hydrogen  will  diffuse  in  the  same  time  as  1 
volume  of  carbon  dioxide,  and  1.34  volumes  of  marsh 
gas  in  the  same  time  as  1  volume  of  air. 

QUESTIONS 

1.  What  is  a  chemical  compound? 

2.  What  is  a  mechanical  mixture? 

3.  Define  atomic  weight. 

4.  What  is  a  chemical  symbol  and  why  are  they  used? 

5.  What  is  the  molecular  weight  of  carbon  dioxide  and 
how  is  it  found? 

6.  The  formula  for  carbon  dioxide  is  C(>2;   in  a  volume 
of  this  gas  what  part  of  its  weight  is  carbon? 

7.  Can  matter  be  destroyed? 

8.  When   we   speak   of   the   relative   humidity   of   the 
air  being  high  what  is  meant? 

9.  If  the  relative  humidity  of  the  air  entering  a  bitu- 
minous mine  is  low  in  what  condition  would  you  expect 
to  find  the  coal  dust? 

10.  What  effect  has  humidity  on  the  explosive  limits 
of  marsh  gas  and  air? 

11.  Describe  the  hygrometer.     What  is  it  used  for? 

12.  What  is  meant  by  diffusion  of  gases? 


GASES  51 

13.  Which   will    diffuse   into   air   more   quickly,  marsh 
gas  or  carbon  monoxide? 

14.  When    liquids    which    do    not    act    chemically    are 
mixed  what  takes  place? 

15.  Will  the  diffusion  of  two  gases  be  quicker  if  the 
difference  between  their  densities  is  great  or  small? 

16.  What  is  the  difference  between  relative  humidity 
and  absolute  humidity? 

17.  Will  evaporation  be  fast  or  slow  when  the  rela- 
tive humidity  is  high? 

18.  When  are  dust  explosions  more  liable  to  occur  in 
bituminous  mines,  summer  or  winter?     Why? 

19.  When  evaporation  is  rapid  does  the  wet-bulb  ther- 
mometer of  the  hygrometer  rise  or  fall? 

20.  What  is  the  specific  gravity  of  saturated  aqueous 
vapor? 

21.  There  are  two  intake  shafts  at  a  mine,  the  rela- 
tive humidity  of  the  air  in  one  is  90  per  cent  and  in  the 
other  40  per  cent.     The  depths  and  other  conditions  being 
similar  through  which  will  the  most  air  flow?     Why? 

22.  What  should  be  the  relative  humidity  of  the  air 
in  living  rooms? 

23.  If   the  dry-bulb  of  a  hygrometer  reads  60  degrees 
and  the  wet-bulb  55  degrees,  what  is  the  relative  humidity? 

24.  A  steam  jet  is  placed  in  an  upcast  shaft,  the  tem- 
perature is  increased  8  degrees  and  the  relative  humidity 
is    increased    40    per    cent.     Does    the    increased    relative 
humidity  assist  in  increasing  the  quantity  of  air.    Explain. 

25.  Will  a  wet  road  in  a  mine  dry  sooner  if  the  velocity 
of  the  air  is  high  or  if  it  is  low?     Why? 


CHAPTER  VIII 
BAROMETER 

48.  There  are  two  kinds  of  barometers  in  use,  the 
mercurial  barometer  and  the  aneroid  barometer.  The 
aneroid,  owing  to  its  portable  form  and  great  sensitive- 
ness in  responding  to  changes  in  pressure  of  the  atmos- 
phere, is  to-day  in  more  general  use  than  any  other  form 
of  barometer.  It  will  denote  a  change  much  quicker 
than  the  mercurial  barometer. 

In  measuring  altitudes,  owing  to  its  portability,  sen- 
sitiveness and  ease  with  which  approximate  results  may 
be  obtained,  it  is  highly  valuable  to  the  engineer  and  sur- 
veyor. 

The  illustration  (Fig.  6)  shows  the  general  construction 
of  the  movement  with  its  elastic  metallic  box  called  the 
vacuum  chamber,  A. 

The  chamber  is  constructed  with  two  circular  discs 
of  thin  corrugated  German  silver  firmly  soldered  together 
at  the  edges,  forming  a  closed  box  as  shown  in  Fig.  7.  The 
air  is  exhausted  from  this  box,  which  causes  the  top  and 
bottom  discs  to  close  together  as  shown  in  Fig.  8.  The 
pressure  of  the  air  upon  the  outside  surface  of  an  ordinary 
size  chamber  is  equal  to  a  force  of  about  60  Ibs. 

The  vacuum  chamber  A  is  firmly  fixed  to  the  circular 
metal  base  B  by  a  post  upon  its  center  projecting  through 
the  base  plate. 

An  iron  bridge  C  spans  the  chamber,  resting  upon 
the  base  plate  by  means  of  the  two  pointed  screws,  c'c. 

52 


BAROMETER 


53 


(These  screws  are  used  to  regulate  the  tension  upon  the 
chamber  A.) 

To  the  bridge  C  is  fixed  the  mainspring  D,  which  is 
forced  down  by  mechanical  means  sufficient  to  insert  the 
knife-edge  piece,  e. 

As  this  knife  edge  is  fastened  (by  means  of  a  central 
pillar)  to  the  top  disc  of  chamber  A,  the  mainspring  D 


FIG.  6. 


.(W 


FIG.  7. 


FIG.  8. 


when  released  lifts  the  upper  part  of  the  chamber,  drawing 
the  two  discs  asunder  so  that  the  box  again  has  the  appear- 
ance as  shown  in  Fig.  7. 

As  this  forms  a  perfect  balance  (the  power  of  the  main- 
spring opposing  the  atmospheric  pressure  upon  the  vacuum 
chamber)  any  variation  in  air  pressure  will  now  be  shown 
by  a  movement  up  or  down  of  the  elastic  chamber.  A 
decrease  in  pressure  will  allow  the  mainspring  to  over- 
come the  power  of  the  vacuum,  the  action  then  being 


54 


MINING  AND  MINE  VENTILATION 


upwards,  and  an  increase  of  air  pressure  will  produce  the 

contrary  result. 

This  vertical  action  of  the  vacuum  cham- 
ber is  multiplied  and  converted  to  a  horizontal 
movement  of  the  indicating  hand  by  a  series  of 
mechanical  movements. 

As  there  is  sometimes  a  settlement  of  some 
of  the  metal  parts  and  springs  which  alters 
the  position  of  the  indicating  hand,  it  is 
advisable,  whenever  an  opportunity  offers,  to 
compare  the  readings  of  an  aneroid  with  a  stand- 
ard mercurial  barometer.  If  they  do  not  agree 
the  aneroid  may  be  adjusted  by  turning  the 
small  adjusting  screw  until  the  indicating  hand 
pn  the  dial  coincides  with  the  height  of  the 
mercury  column. 


FIG.  9. 


FIG;  10. 


In  the  best  made  instruments  the  main  lever  G  is  made 
of  a  composite  bar  of  two  metals,  steel  and  brass,  the  quan- 


BAROMETER  55 

tity  of  each  metal  being  altered  until  it  is  correctly  com- 
pensated for  any  change  in  temperature.  This  averts 
the  necessity  of  making  allowances  for  changes  in  tem- 
perature, as  is  necessary  in  reading  a  mercurial  barometer. 

The  divisions  upon  the  scale  of  an  aneroid  barometer 
represents  inches  and  fractions  of  an  inch  of  atmospheric 
pressure,  the  scale  being  determined  by  comparison  with 
a  mercury  column  as  explained. 

The  words  "storm,"  "fair,"  "rain,"  etc.,  upon  the 
dial  are  simply  relatives,  as  it  does  not  follow  that  the 
weather  conditions  indicated  by  these  words  will  neces- 
sarily exist  when  the  indicating  hand  of  the  barometer 
points  to  them.  The  meaning,  for  example,  when  the 
hand  points  to  the  word  "fair,"  is  that  the  atmospheric 
pressure  at  that  time  is  favorable  to  fair  weather. 

The  mercurial  barometer  consists  of  a  glass  tube  about 
34  ins.  long.  The  tube  is  closed  at  one  end  and  filled  with 
mercury;  it  is  then  inverted  with  its  lower  end  constantly 
below  the  surface  of  the  mercury  in  a  vessel  fixed  at  the 
bottom.  Figs.  9  and  10  show  the  mercurial  and  aneroid 
barometers  ready  for  use. 

49.  Atmospheric  Pressure. — The  average  pressure  of 
the  atmosphere  at  sea  level  is  14.7  Ibs.  per  square  inch. 
This  is  called  the  pressure  of  1  ATMOSPHERE. 

If  the  area  of  a  cross-section  of  the  barometer  tube 
is  1  sq.in.  there  should  be  30  cu.ins.  of  mercury  in  a  column 
30  ins.  high.  As  a  cubic  inch  of  mercury  weighs  .49  Ib. 
the  whole  column  would  weigh  30 X. 49  =  14.7  Ibs. 

EXAMPLE. — If  the  barometer  reads  28  inches,  what  is 
the  atmospheric  pressure? 

Solution.— 28 X. 49  =  13.72  Ibs.  per  sq.in. 

If  a  liquid  less  dense  than  mercury  is  used  the  column 
will  be  correspondingly  longer.  Hence,  if  water  be  used 
instead  of  mercury  the  column  at  sea  level  would  be 


56  MINING  AND  MINE  VENTILATION 

408    inches,    since    mercury   is    13.6    times    as    heavy   as 
water. 

EXAMPLE. — If  the  mercury  column  is  29  inches,  what 
would  be  the  height  of  a  water  column  under  the  same 
pressure? 

13.6X29  =  394.4  ins.     Ans. 

The  pressure  of  the  atmosphere  on  the  top  of  a  high 
mountain  is  less  than  at  sea  level  and  it  is  greater  at  the 
bottom  of  a  shaft  than  at  the  top.  If  the  barometer  reads 

29  inches  at  the  top  of  a  shaft  and  at  the  bottom  it  reads 

30  inches,  the  shaft  is  about  900  feet  deep,  as  the  difference 
of  900  feet  in  altitude  means  a  rise  or  fall  of  approximately 
1  inch  of  barometer. 

50.  Use   of   a   Barometer   in  a  Mine. — The  barometer 
is  an  instrument  of  great  importance  in  mines  where  explo- 
sive gases  are  generated,  as  an  increase  or  decrease  in  the 
atmospheric  pressure  is  instantly  indicated  by  the  aneroid 
(not   so  quickly  by  the  mercurial).     Hence,   in   case  the 
barometer  drops  1  inch  this  will  mean  a  reduction  of  .49 
Ib.  on  every  square  inch  of  surface  in  the  mine,  thereby 
allowing  the  occluded  gases  in  the  coal  to  escape  more 
freely. 

At  some  of  the  anthracite  mines  of  Pennsylvania  the 
barometer  is  located  in  a  convenient  place  on  the  surface 
and  the  readings  are  recorded  three  times  each  day.  In 
case  the  barometer  indicates  a  decrease  in  pressure,  the 
person  in  charge  of  the  mine  is  notified  of  the  impending 
danger. 

51.  Use   of   the   Aneroid   in   Determining  Altitudes.— 
When  a  compensated  barometer  is  used  it  is  not  necessary 
to    make    allowance   for   temperature.     Before    taking    an 
altitude  reading  the  0  of  the  altitude  scale  should  always 
be  opposite  31  inches  on  the  barometer  dial. 


BAROMETER  57 

For  example,  suppose  the  aneroid  indicated  a  pressure 
of  29  inches,  and  if  we  ascend  a  hill  and  the  hand  (by  reason 
of  a  decreasing  pressure)  moves  to  25  inches,  the  method 
of  determining  the  difference  in  altitude  is  as  follows: 
The  value  of  29  inches  with  the  0  of  the  outer  rim  at  31 
is  about  1800  feet,  while  the  value  of  25  inches  under  the 
same  conditions  is  5850  feet. 

5850-1800  =  4050,  the  difference  in  altitude. 

Now  suppose  the  barometer  indicates  a  pressure  of  29 
inches,  but  instead  of  having  the  0  feet  at  31  inches,  we 
move  the  milled  ring  so  that  the  0  feet  is  standing  opposite 
29  inches.  If  the  observer  then  ascends  a  mountain  until 
the  hand  moves  to  25  inches  the  altitude  registered  will 
be  only  3750  feet,  or  300  feet  in  error. 

The  graduations  on  the  altitude  scale  of  an  aneroid 
gradually  diminish  in  size.  The  first  inch  of  pressure, 
from  31  inches  to  30  inches,  represents  an  ascent  of  about 
900  feet,  while  an  inch  of  pressure,  from  26  inches  to  25 
inches,  represents  about  1050  feet. 

Difference  in  altitude  cannot  be  accurately  determined 
by  means  of  the  barometer  in  the  mine  workings,  because 
there  is  always  a  difference  in  pressure  between  the  intake 
and  return  airways. 

If  in  case  of  an  exhaust  fan  ventilating  a  mine, 
the  barometer  is  carried  through  the  intake  and  back 
through  the  return  to  the  fan,  it  will  be  found  that  the 
barometer  gradually  falls  as  the  distance  to  the  fan 
decreases. 

Stepping  from  an  intake  airway  through  a  door  to  the 
return  airway  will  cause  a  fall  in  the  barometer  equal  to 
the  difference  in  pressure  between  the  two  airways.  Under 
such  conditions  the  barometer  might  show  a  difference  of 


58 


MINING  AND  MINE  VENTILATION 


100  feet  in  elevation,  while  in  reality  the  elevations  of  both 
roads  are  the  same. 


TABLE   H 
PROFESSOR   AIREY'S   TABLE 


OF   ALTITUDES 


Barom- 
eter in 
Inches. 

Height 
in  Ft. 

Barom 
eter  in 
Ins. 

Height 
in  Ft. 

Barom- 
eter in 
Ins. 

Height 
in  Ft. 

Barom- 
eter in 
Ins. 

Height 
in  Ft. 

31.00 

0 

28.28 

2500 

25.80 

5000 

23.54 

7500 

30.94 

50 

28.23 

2550 

25.75 

5050 

23.50 

7550 

30.88 

100 

28.18 

2600 

25.71 

5100 

23.45 

7600 

30.83 

150 

28.12 

2650 

25.66 

5150 

23.41 

7650 

30.77 

200 

28.07 

2700 

25.61 

5200 

23.37 

7700 

30.71 

250 

28.02 

2750 

25  .  56 

5250 

23.32 

7750 

30.66 

300 

27.97 

2800 

25.52 

5300 

23.28 

7800 

30.60 

350 

27.92 

2850 

25.47 

5350 

23.24 

7850 

30.54 

400 

27.87 

2900 

25.42 

5400 

23.20 

7900 

30.49 

450 

27.82 

2950 

25.38 

5450 

23.15 

7950 

30.43 

500 

27.76 

3000 

25.33 

5500 

23  .  1  1 

8000 

30.38 

550 

27.71 

3050 

25.28 

5550 

23.07 

8050 

30.32 

600 

27.66 

3100 

25.24 

5600 

23.03 

8100 

30.26 

650 

27.61 

3150 

25.19 

5650 

22.98 

8150 

30.21 

700 

27.56 

3200 

25.15 

5700 

22.94 

8200 

30.15 

750 

27.51 

3250 

25.10 

5750 

22.90 

8250 

30.10 

800 

27.46 

3300 

25.05 

5800 

22.86 

8300 

30.04 

850 

27.41 

3350 

25.01 

5850 

22.82 

8350 

29.99 

900 

27.36 

3400 

24.96 

5900 

22.77 

8400 

29.93 

950 

27.31 

3450 

24.92 

5950 

22.73 

8450 

29.88 

1000 

27.26 

3500 

24.87 

6000 

22.69 

8500 

29.82 

1050 

27.21 

3550 

24.82 

6050 

22.65 

8550 

29.77 

1100 

27.16 

3600 

24.78 

6100 

22.61 

8600 

29.71 

1150 

27.11 

3650 

24.73 

6150 

22.57 

8650 

29.66 

1200 

27.06 

3700 

24.69 

6200 

22.52 

8700 

29.61 

1250 

27.01 

3750 

24.64 

6250 

22.48 

8750 

29.55 

1300 

26.96 

3800 

24.60 

6300 

22.44 

8800 

29.50 

1350 

26.91 

3850 

24.55 

6350 

22.40 

8850 

29.44 

1400 

26.86 

3900 

24.51 

6400 

22.36 

8900 

29.39 

1450 

26.81 

3950 

24.46 

6450 

22.32 

8950 

29.34 

1500 

26.76 

4000 

24.42 

6500 

22.28 

9000 

29.28 

1550 

26.72 

4050 

24.37 

6550 

22.24 

9050 

29.23 

1600 

26.67 

4100 

24.33 

6600 

22.20 

9100 

29.17 

1650 

26.62 

4150 

24.28 

6650 

22.16 

9150 

29.12 

1700 

25.57 

4200 

24.24 

6700 

22.11 

9200 

29.07 

1750 

26.52 

4250 

24.20 

6750 

22.07 

9250 

29.01 

1800 

26.47 

4300 

24.15 

6800 

22.03 

9300 

28.96 

1850 

26.42 

4350 

24.11 

6850 

21.99 

9350 

28.91 

1900 

26.37 

4400 

24.06 

6900 

21.95 

9400 

28.86 

1950 

26.33 

4450 

24.02 

6950 

21.91 

9450 

28.80 

2000 

26.28 

4500 

23.97 

7000 

21.87 

9500 

28.75 

2050 

26.23 

4550 

23.93 

7050 

21.83 

9550 

28.70 

2100 

26.18 

4600 

23.89 

7100 

21.79 

9600 

28.64 

2150 

26.13 

4650 

23.84 

7150 

21.75 

9650 

28.59 

2200 

26.09 

4700 

23.80 

7200 

21.71 

9700 

28.54 

2250 

26.04 

4750 

23.76 

7250 

21.67 

9750 

28.49 

2300 

25.99 

4800 

23.71 

7300 

21.63 

9800 

28.43 

2350 

25.94 

4850 

23.67 

7350 

21.59 

9850 

28.38 

2400 

25.89 

4900 

23.62 

7400 

21.55 

9900 

28.33 

2450 

25.85 

4950 

23.58 

7450 

21.51 

9950 

BAROMETER  59 

BAROMETRIC  INDICATIONS. — The  barometer  not  only 
indicates  an  increased  or  decreased  pressure  on  the  occluded 
gases  in  the  pores  of  the  coal,  or  determines  the  height 
of  mountains  or  depth  of  shafts,  but  also  forecasts  the 
weather. 

A  rapid  fall  or  a  rapid  rise  of  the  barometer  indicates 
that  a  strong  wind  is  about  to  blow  and  that  this  wind  will 
bring  with  it  a  change  in  the  weather.  What  the  nature 
of  the  change  will  be  will  depend  upon  the  direction  from 
which  the  wind  blows. 

If  an  observer  stands  facing  the  wind  the  locality  of 
low  barometric  pressure  will  be  at  his  right  and  that  of 
high  barometric  pressure  at  his  left.  With  low  pressure 
in  the  west  and  high  pressure  in  the  east,  the  winds  will 
be  from  the  south;  but  with  low  pressure  in  the  east  and 
high  pressure  in  the  west,  the  wind  will  be  from  the  north. 

A  slow  but  steady  rise  indicates  fair  weather. 

A  slow  but  steady  fall  indicates  unsettled  or  wet  weather. 

A  rapid  rise  indicates  clear  weather  with  high  winds. 

A  very  slow  fall  from  a  high  point  indicates  wet  and 
unpleasant  weather  without  much  wind. 

A  sudden  fall  indicates  a  sudden  shower  or  high  winds 
or  both. 

When  a  barometer  falls  considerably  without  any 
precise  change  of  weather  it  may  be  certain  that  a  storm 
is  raging  at  a  distance. 

A  stationary  barometer  indicates  a  continuance  of 
existing  conditions,  but  a  slight  tap  on  the  barometer 
face  will  likely  move  the  hand  a  trifle,  indicating  whether 
the  tendency  is  to  rise  or  fall. 

The  principal  maximum  barometer  pressure  occurs 
before  noon  and  the  principal  minimum  after  noon. 

EXAMPLE. — If  the  barometer  reading  is  30  inches, 
(a)  what  is  the  pressure  per  square  inch  on  the  face  and 


60  MINING  AND  MINE  VENTILATION 

sides  of  a  chamber  in  a  mine?     (6)  If  the  reading  is  28 

inches,  what  is  the  pressure? 

Am.  (a)  14.7  Ibs. 

(6)  13.72  Ibs. 

By  the  above  example  it  is  readily  seen  that  as  the 
pressure  per  square  inch  is  less  with  a  barometer  of  28 
inches  than  with  a  barometer  of  30  inches,  a  larger  volume 
of  gas  will  escape  from  fissures  and  pores  of  the  coal,  thus 
rendering  the  mine  atmosphere  more  dangerous  than  if 
the  barometer  stood  at  30  inches. 

52.  Effect  of  Temperature  and  Pressure  on  Volume 
of  Gases. — CHARLES'  LAW. — It  has  been  found  by  experi- 
ment that  under  constant  pressure  all  gases  expand  or 
contract  equally  for  equal  changes  of  temperature.  More 
explicitly,  a  gas  expands  or  contracts  1/491  of  its  volume 
at  32°  F.,  for  every  degree  through  which  it  is  heated  or 
cooled.  This  means  that  491  cubic  feet  of  gas  at  32°  F. 
becomes  492  cubic  feet  at  33°  F.,  490  at  31°  F. 

BOYLE'S  LAW. — It  has  been  found  by  experiment  that 
under  constant  temperature  the  volume  of  a  gas  is  inversely 
proportional  to  the  pressure.  This  means  that  doubling 
the  pressure  halves  the  volume,  and  vice  versa.  If  a 
gas  is  under  a  certain  pressure  and  the  pressure  is  dimin- 
ished to  J,  f,  |,  etc.,  of  its  original  pressure,  the  gas  will 
increase  in  volume  2,  4,  8,  etc.,  times.  Its  tension  increas- 
ing the  volume  will  decrease  at  the  same  rate. 

EXAMPLE. — If  6  cu.ft.  of  air  be  under  a  pressure  of 
10  Ibs.  (a)  what  will  be  the  volume  when  the  pressure  is 
20  Ibs.?  (6)  when  the  pressure  is  5  Ibs.,  temperature  remain- 
ing the  same? 

(a)  vol.  =  ^5=   3  cu.ft. 

6X10 
(6)  vol.  =  — - —  =  12  cu.ft. 


BAROMETER  61 

It  should  be  remembered  that,  when  the  temperature 
remains  the  same,  the  volume  of  a  given  quantity  of  gas  varies 
inversely  as  the  pressure. 

By  means  of  the  following  formula  the  increased  or 
decreased  volume  of  a  gas,  due  to  an  increase  or  decrease 
in  the  temperature,  can  be  found,  pressure  remaining  con- 
stant. 

Let  v  —  volume  of  gas  before  heating; 
v'  =  volume  of  gas  after  heating; 
t  =  temperature  corresponding  to  volume  v ; 
t'  =  temperature  corresponding  to  volume  vf. 
Thus, 

459+O 


v  =  v 


(459+0 


EXAMPLE. — If  10  cubic  feet  of  air  at  a  temperature  of 
40°  is  heated  under  constant  pressure  until  the  temper- 
ature reaches  150°,  what  is  the  new  volume? 

,       459+150  (609)  ,. 

"-"  459+40  =1°X (499)  =  12.20  cu.ft. 

53.  Absolute  Zero. — The  atoms  and  molecules  of  all 
bodies  are  in  a  constant  state  of  vibration.  An  increase 
of  heat  will  increase  this  vibratory  movement  and  a  decrease 
of  heat  will  have  the  opposite  effect.  This  vibratory 
movement  will  continue,  however,  until  a  temperature 
459°  F.  below  zero  is  reached,  at  which  point  the  movement 
will  cease.  459°  F.  is  called  absolute  zero. 

No  one  has  ever  succeeded  in  depriving  a  body  of  all 
its  heat  or  cooling  it  to  absolute  zero,  though  some  exper- 
iments have  come  within  10°  of  it;  nevertheless,  it  has  a 
meaning  and  is  used  in  many  formulas. 

EXAMPLE. — If  10,000  cu.ft.  of  air  enters  a  mine  at  a 


62  MINING  AND  MINE  VENTILATION 

temperature  of  30°  F.,  what  volume  will  leave  the  mine 
if  the  temperature  in  the  return  airway  is  70°  F. 

Ans.     10,818  cu.ft.  nearly. 

ABSOLUTE  TEMPERATURE. — If  the  absolute  temperature 
of  a  gas  is  known  the  ordinary  temperature  may  be  found 
by  subtracting  459°  from  the  absolute  temperature. 

EXAMPLE. — If  the  absolute  temperature  of  a  quantity  of 
air  is  500°  F.,  the  ordinary  temperature  is  500°-459°  =  41°  F. 

The  pressure,  volume,  temperature  or  weight  of  air 
can  be  found  by  the  following  formulas,  in  which 

P  =  pressure  per  square  inch ; 
V  =  volume  of  air  in  cubic  feet; 
T  =  absolute  temperature ; 
W  =  weight  of  the  air; 
.37052TF77 


T  = 


P 
PV 


.37052TF 

PV 
~.37052r 

EXAMPLE. — If  20  cubic  feet  of  air  weighs  2  pounds 
and  the  temperature  is  60°  F.,  what  is  the  pressure  or 
tension  in  pounds  per  square  inch? 

.37052TFT'     .37052X2X519 

Solution. — P  = = =  -         ort         —  =  19.23      per 

V  A\J 

sq.in.  nearly.     Ans. 

EXAMPLE. — The  temperature  of  a  certain  quantity  of 
a  ir  is  60°  F.  Its  weight  is  2  Ibs.  and  the  pressure  per  square 
inch  is  19.23  Ibs.  What  is  the  volume? 


BAROMETER  63 

.37052F77     .37052X2X519     on       ., 
Solution.—  V  =  --  p  --  =  -    ~To~23~~   ~~  =       C 

Ans. 

EXAMPLE.  —  If  20  cubic  feet  of  air  have  a  (pressure) 
tension  of  19.23  Ibs.  per  square  inch  and  weighs  2  Ibs., 
what  is  the  temperature? 


rp_ 


Solution. 

19.23X20 


.37052TF-.  37052X2 


EXAMPLE. — If  20  cubic  feet  of  air  have  a  tension  of 
19.23  Ibs.  and  a  temperature  of  60°  F.,  what  is  the  weight? 

PV          19.23X20 

2  lbs'        An8' 


If  a  certain  quantity  of  gas  be  heated  through  any 
number  of  degrees  and  the  volume  remains  the  same  the 
tension  or  pressure  will  increase.  For  example,  if  a  volume 
of  gas  is  confined  in  a  cylinder  and  if  the  gas  is  heated, 
its  tendency  to  expand  is  prevented  by  the  sides  of  the  cyl- 
inder, consequently,  the  tension  or  pressure  of  the  gas 
is  increased.  It  will  be  found  that  for  every  increase  of 
temperature  of  1°  F.  there  will  be  an  increase  of  ^ir  of 
the  original  tension  at  32°  F. 

If  the  gas  is  free  to  expand  adding  heat  will  increase 
the  volume  and  the  tension  will  remain  constant. 

EXAMPLE. — If  a  quantity  of  gas  is  heated  from  30°  F. 
to  70°  F.,  the  volume  remaining  constant  (that  is  the 
volume  enclosed  so  it  cannot  expand),  what  is  the  result- 
ing tension  if  the  original  tension  was  14.7  Ibs.  per  square 
inch? 


64  MINING  AND  MINE  VENTILATION 

p  =  original  tension; 
t  =  original  temperature; 
£'  =  any  temperature; 
p'  =  corresponding  tension. 

.(459+Q 
P      P 


(459  +t)  ' 
_  (459+70)          .(529) 


P  = 


EXAMPLE.  —  If  a  quantity  of  gas  is  heated  under  con- 
stant volume  from  30°  F.  to  100°  F.,  what  is  the  resultant 
tension,  the  original  tension  being  equal  to  one  atmos- 
phere? 

The  term  "  a  pressure  of  one  atmosphere  "  is  sometimes 
used  as  a  unit  of  pressure;  it  means  14.7  Ibs.  Thus,  two 
atmospheres  mean  a  pressure  of  29.4  Ibs.  per  sq.in. 

54.  Calculation  of  the  Weight  of  a  Gas  at  Different 
Temperatures  and  Pressures.  —  The  weight  per  cubic 
foot  of  any  gas  at  different  temperatures  and  pressures 
can  be  found  by  the  following  formula: 


Let  W  =  weight  in  pounds; 
V  =  volume  in  cubic  feet; 
B  =  barometric  pressure; 
S  =  specific  gravity; 
T  =  absolute  temperature. 


EXAMPLE. — If  250  persons  are  employed  in  a  mine 
and  each  person  is  allowed  200  cubic  feet  of  air  per  minute, 
what  is  the  weight  in  tons  of  the  air  passing  through  the 
mine  in  10  hours,  the  temperature  being  60°  F.  and  the 
barometer  30  inches? 

x  Solution.— 250X200X60X10  =  30,000,000  cu.ft. 


BAROMETER  65 

weight  per  cu,t. 


EXAMPLE.  —  What  is  the  weight  of  100  cubic  feet  of 
carbon  dioxide  gas  at  a  pressure  of  30  inches  and  a  tem- 
perature of  30°  F.? 

NOTE.  —  The  constant,  1.3253,  is  the  weight  in  pounds 
of  one  cubic  foot  of  air  at  1°  absolute  temperature  (F.) 
and  1  inch  barometer. 


w 

Solution.  —  W 


QUESTIONS 

1.  What  do  we  mean  when  we  say  a  barometer  is  com- 
pensated? 

2.  What  is  the  meaning  of  the  words  "  stormy,"  "  fair," 
"  rain,"  etc.,  upon  the  dial  of  an  aneroid  barometer? 

3.  Which  will  denote  a  change  in  pressure  more  quickly, 
the  aneroid  or  mercurial  barometer? 

4.  What  is  the  weight  of  a  cubic  inch  of  mercury? 

5.  Why  is  mercury  used  in  a  barometer  instead  of  some 
other  liquid? 

6.  What   is   the   average   pressure   of   the   atmosphere 
per  square  inch  at  sea  level? 

7.  If  2  cubic  feet  of  air  are  under  a  pressure  of  50  Ibs. 
per  square  inch,  (a)  what  will  be  the  pressure  when  the 
volume  is  increased  to  5  cubic  feet?    (6)  to  3  cubic  feet? 


66  MINING  AND  MINE  VENTILATION 

8.  If  20  cubic  feet  of  air  have  a  tension  of  6  Ibs.  per 
square  inch,   (a)  what  is  the  volume  when  the  tension  is 
5  Ibs.?     (6)  10  Ibs.?     (c)  15  Ibs.? 

9.  The  weight  of  1  cubic  foot  of  air  at  a  temperature 
of  60°  F.  and  under  a  pressure  of  1  atmosphere  (14.7  Ibs. 
per  square   inch)  is  .0766  lb.,  what  would  be  the  weight  per 
cubic  foot  if  the  volume  be  compressed  until  the  tension 
is  6  atmospheres,  temperature  remaining  the  same? 

10.  If  in  the  last  example  the  air  had  expanded  until 
the  tension  was  10  Ibs.  per  square  inch,  what  would  have 
been  its  weight  per  cubic  foot? 

11.  If  10  cubic  feet  of  air  at  a  temperature  of  60°  F. 
and  a  pressure  of  1  atmosphere  are  compressed  to  4  cu.ft. 
(temperature  remaining  the  same)  what  is  the  weight  of 
a  cubic  foot  of  the  compressed  air? 

12.  When  5  cubic  feet  of  air  at  a  temperature  of  40°  F. 
are  heated  under  constant  pressure  up  to  150°  F.,  what 
is  the  new  volume? 

13.  What  is  the  weight  of  100  cubic  feet  of  air  at  a 
temperature  of  60°,  barometer  30  inches? 

14.  What  is  the  weight  of  100  cubic  feet  of  marsh  gas 
(conditions  same  as  question  13)? 

15.  What  is  the  weight  of  (a)  100  cubic  feet  of  carbon 
dioxide,   (6)   100  cubic  feet  of  carbon  monoxide  (temper- 
ature and  pressure  same  as  in  question  13)? 

16.  Which  is  the  more  dense,    (a)   air  or  marsh  gas, 
(b)  air  or  carbon  dioxide? 

17.  There  are  two  shafts  connected  under  ground  and 
so  located  that  the  barometer  reading  at  the  top  of  the 
first  shaft  is  29  ins.  and  at  the  top  of  the  second  shaft 
30  ins.;  the  temperature  in  the  first  shaft  is  60°  and  in  the 
second  100°,  in  what  direction  will  the  air  move  (natural 
ventilation)  ? 

18.  If  water  were  used  in  the  construction  of  a  barom- 


BAROMETER  67 

eter,  what  would  be  the  height  of  a  water  barometer  when 
the  mercurial  barometer  stands  at  30  ins.?   at  25  ins.? 

19.  Explain  the  principle  involved  in  using  the  barom- 
eter to  measure  elevations. 

20.  Why  do  we  not  feel  the  pressure  of  the  atmosphere? 


CHAPTER  IX 
GASES 

55.  Acetylene  Gas. — Acetylene  burns  in  the  air  with 
a  smoky,  luminous  flame,  but  when  air  is  mixed  with  the 
gas  as  it  issues  from  a  small  opening  such  as  the  jet  of  a 
miner's  lamp,  the  mixture  burns  with  a  brilliant  white 
flame  which  does  not  smoke,  in  view  of  which  the  lamp 
is  now  used  quite  extensively  in  the  mines.  The  flame 
is  much  smaller  than  an  ordinary  gas  flame  of  the  same 
lighting  power. 

Acetylene  is  generated  by  putting  calcium  carbide 
into  a  flask  and  allowing  water  to  drop  slowly  upon  the 
carbide.  A  pound  of  calcium  carbide  yields  about  5 
cubic  feet  of  acetylene  gas.  The  formula  for  acetylene 
is  C2H2. 

Acetylene  is  slightly  poisonous,  though  very  much  less 
so  than  carbon  monoxide.  Investigations  made  by  the 
Bureau  of  Mines  with  acetylene  generated  from  carbide 
such  as  is  used  in  a  miner's  lamp,  indicate  that  there  is 
little  if  any  chance  of  men  being  poisoned  because  of  the 
use  of  acetylene  in  mines.  Acetylene,  of  course,  is  suffo- 
cating, as  are  carbon  dioxide,  nitrogen  and  hydrogen. 

Calcium  carbide  is  made  by  heating  a  mixture  of  lime 
and  coke  in  an  electric  furnace.  It  is  a  hard,  brittle  solid; 
its  specific  gravity  is  2.2.  Owing  to  its  action  with  water, 
it  should  be  packed  in  air-tight  cans.  Fig.  11  shows  the 
style  lamp  used  in  the  mines  for  lighting  purposes. 

The  acetylene  lamp  will  burn  in  air  that  contains  only 

68 


GASES  69 

10  to  11  per  cent  of  oxygen,  a  proportion  which  is  much 
too  low  to  support  the  flame  of  an  ordinary  oil  lamp.  For 
this  reason  objection  has  been  made  to  the  use  of  acety- 
lene lamps  in  mines,  because  they  may  not  warn  the  miners 
that  the  atmosphere  is  so  low  in  oxygen  as  to  cause  them 
immediate  harm.  If  a  man  exerts  himself  in  such  atmos- 
phere his  labored  breathing  warns  him  that  the  air  is  not 


FIG.  11. 

fit  to  breathe.  The  best  authorities  agree  that  a  man  will 
live  without  serious  inconvenience  in  an  atmosphere  where 
the  oxygen  is  reduced  to  10  per  cent.  Deficiency  of  oxygen 
becomes  a  real  danger  when  it  is  as  low  as  7  or  8  per  cent. 
The  acetylene  flame  is  extinguished  before  the  danger  point 
is  reached  and  the  suggestion  that  it  does  not  give  adequate 
warning  by  extinction  in  an  atmosphere  low  in  oxygen  has 
been  disproved  not  only  scientifically  but  practically. 


70 


MINING  AND  MINE  VENTILATION 


PERCENTAGE  TO  WHICH  OXYGEN   MUST   BE  REDUCED 
TO  EXTINGUISH  VARIOUS  FLAMES 

Coirbustible.  Percentage  of  Oxygen. 

Candle 16  to  17 

Benzine 16  to  17 

Hydrogen 7  to    8 

Acetylene 10  to  11 

Petroleum 16  to  17 

56.  Safety  Lamps. — It  frequently  happens  that  an 
explosive  mixture  of  gases  accumulates  in  coal  mines.  An 
ordinary  lamp  brought  in  contact  with 
this  mixture  would  cause  an  explosion. 
To  prevent  this  and  still  make  it 
possible  to  use  a  light,  Sir  Hum- 
phry Davy  devised  a  form  of  lamp 
(Fig.  12)  in  which  the  flame  is  en- 
tirely surrounded  with  wire  gauze. 
Whenever  the  lamp  is  brought  into 
an  inflammable  mixture  of  gases  some 
of  the  mixed  gas  will  enter  the  lamp 
and  burn  there.  But  the  heat  is  ab- 
sorbed by  the  gauze  to  such  an 
extent  that  the  gas  outside  the  lamp 
does  not  receive  heat  enough  to  ignite 
until  the  gauze  becomes  so  heated 
that  it  cannot  take  any  more  heat 
from  the  burning  gas;  the  flame  will 
then  pass  through  the  gauze  and 
ligct  the  gas  in  the  surrounding  atmosphere. 

The  standard  adopted  as  a  limit  of  safety  was  iron  wire 
gauze  with  784  meshes  per  square  inch,  the  wires  being 
about  ^V  inch  in  thickness.  In  a  dangerous  atmosphere 
the  entire  space  within  the  gauze  becomes  occupied  with 
flame;  under  such  condition  the  lamp  should  be  removed 


FIG.  12. 


GASES  71 

carefully  from  the  gaseous  mixture,  making  no  quick  move- 
ments while  doing  so. 

Modifications  of  the  Davy  lamp  have  come  into  use, 
chiefly  with  a  view  to  surrounding  the  flame  with  glass 
so  as  to  increase  the  effective  radiation  of  light;  but  in 
each  case  ingress  and  egress  of  air  are  effected  through 
one  or  more  thicknesses  of  wire  gauze. 

The  lamps  most  commonly  used  are  the  Davy,  Clanny 
and  Wolf.  The  features  most  desired  in  a  safety  lamp 
are  (1)  safety  in  strong  currents;  (2)  maximum  illumi- 
nating power;  (3)  security  of  lock;  (4)  so  constructed 
that  it  can  be  relighted  without  opening  the  lamp;  (5) 
simplicity  of  construction. 

67.  Occlusion  of  Gases. — A  gas  is  occluded  when  it 
is  absorbed  and  pent  up  in  the  pores  of  any  substance. 
Hydrogen  is  absorbed  freely  by  several  metals,  especi- 
ally platinum  and  palladium.  Gases  exist  in  varying 
quantities  in  coal  seams;  those  most  commonly  occluded 
in  the  coal  are  marsh  gas  or  methane,  carbon  dioxide, 
nitrogen,  oxygen  and  ethane.  The  pressure  of  the  occluded 
gases  is  sometimes  as  high  as  12  to  15  atmospheres. 

In  newly-exposed  coal  faces  the  gas  can  be  heard  and 
felt  exuding  from  the  pores.  Many  cases  are  recorded 
where  the  flow  of  gas  from  coal  seams  was  so  strong  that 
a  formerly  reasonably  safe  atmosphere  became  in  a  short 
time  explosive. 

The  writer  has  many  times  heard  it  said  that  in  some 
mines  gas  exudes  with  such  force  from  the  coal  seams  that 
it  prevents  the  movement  of  the  air.  This  is  due,  not  to 
the  force  with  which  the  gas  is  emitted,  but  to  the  volume 
of  gas  given  off. 

To  remove  a  large  body  of  firedamp  it  would  require  a 
pressure  much  greater  than  the  average  mine  fan  now  in 
operation  can  produce. 


72  MINING  AND  MINE  VENTILATION 

58.  Properties. — All    gases    conform    and    behave    uni- 
formly with  changes  of  pressure  and  with  changes  of  tem- 
perature.    Thus  if  the  pressure  on  a  certain  volume  of 
marsh  gas  be  doubled  the  volume  will  be  reduced  one-half, 
and  if  the  pressure  on  a  volume  of  carbon  dioxide  be  doubled 
the   volume   will    also   be   reduced    one-half,    temperature 
remaining  the  same.     Also  if  the  temperature  of  several 
gases  be  increased  one  degree  the  amount  of  increase  in 
volume  will  be  the  same  in  all,  pressure  remaining  the  same. 

There  is  an  equal  number  of  molecules  in  equal  volumes 
of  all  gases  at  the  same  temperature  and  pressure. 
Therefore,  since  one  molecule  of  oxygen  weighs  16  times 
more  than  one  molecule  of  hydrogen,  100  molecules  of 
oxygen  will  weigh  16  times  more  than  100  molecules  of 
hydrogen. 

59.  Physical  Properties  of  Air. — Air  when  pure  is  col- 
orless,   tasteless,    odorless    and    transparent.     It    can    be 
liquefied   by  pressure  at  a  very  low  temperature.     It  is 
14.4  times  as  heavy  as  hydrogen. 

60.  Chemical  Properties  of  Air. — The  formula  for  air  is 
ON4.     Its    oxygen    supports    combustion,    the   energy    of 
which  is  checked  by  the  diluting  nitrogen.     When  air  con- 
taining  carbon  dioxide  is  passed  through  lime-water  the 
carbon  dioxide  renders  the  clean  liquid  milky  in  appear- 
ance. 

61.  Carbon  Monoxide. — This  gas  is  sometimes  called 
white  damp  (CO).     When  burned,  a  blue  flame,  such  as  is 
produced  by  the  burning  of  anthracite  coal,  can  be  seen. 
Carbon   monoxide    is    produced    when    carbon    is    burned 
in  a  limited  supply  of  air. 

62.  Properties. — Carbon    monoxide    is    a    very    pois- 
onous gas;   it'  is  doubly  dangerous  because  its  lack  of  odor 
prevents  its  detection. 

The  gas  is  a  little  lighter  than  air,  its  density  being  14. 


GASES  73 

It  does  not  support  combustion,  but  is  combustible.  It 
burns  with  a  pale  blue  flame  and  yields  carbon  dioxide 
(CO2)  as  the  sole  product  of  its  combustion.  One  per 
cent  of  it  in  the  air  is  fatal  to  life. 

The  best  antidote  is  the  free  inhalation  of  pure  oxygen. 

When  a  lighted  lamp  is  placed  in  an  atmosphere  con- 
taining this  gas  the  flame  brightens  and  lengthens  into  a 
more  or  less  slim  taper  with  a  bluish  tip. 

63.  How   Produced.— Carbon   monoxide   is   a    product 
of  the  incomplete  combustion  of  carbonaceous  fuel  when 
the  supply  of  air  is  limited.     Mine  fires  and  explosions 
of  powder  and  fire  damp  are  the  principal  sources  of  this 
gas  in  mines. 

64.  Explosive     Properties. — Carbon     monoxide     mixed 
with  air  is  explosive,  but  explosions  of  mixtures  of  carbon 
monoxide  and  air  in  mines  are  very  rare.     However,   if 
an  atmosphere  contains  15.5  per  cent  of  carbon  monoxide, 
it   will   explode,   but   such   a  large   percentage   of   carbon 
monoxide  is  seldom  found  in  the  gases  from  a  mine  fire. 
A   mixture   of   carbon   monoxide   and   air   containing   too 
little  carbon  monoxide  to  be  explosive  may  become  explo- 
sive by  the  addition  of  enough  marsh  gas,  even  if  the  pro- 
portion of  marsh  gas  in  the  mixture  be  below  the  explo- 
sive limit  of  marsh  gas  and  air. 

65.  Carbon    Dioxide. — CO2,    commonly  called    "  black 
damp,"  is  a  colorless  gas  and  is  about  one  and  one-half 
times  heavier  than  air,  its  density  being  22. 

On  account  of  its  weight  it  can  be  displaced  and  poured 
from  one  vessel  to  another. 

This  gas  diffuses  very  slowly  on  account  of  its  high 
density,  therefore  it  often  accumulates  in  low  places  in 
mines.  The  gas  is  soluble  in  water  volume  for  volume 
at  ordinary  temperatures  and  pressures.  It  is  not  as 
dangerous  as  carbon  monoxide.  It  can  be  detected  by 


74  MINING  AND  MINE  VENTILATION 

an  ordinary  lamp;  the  light  becomes  dim  and  appears  to 
pull  away  from  the  wick. 

If  air  containing  carbon  dioxide  is  passed  through 
lime-water  the  liquid  becomes  milky.  The  exhausts  from 
gasoline  engines  used  in  mines  are  sometimes  so  arranged 
that  they  exhaust  through  lime-water.  The  carbon  dioxide 
unites  with  the  lime  in  the  water  and  is  thereby  prevented 
from  being  discharged  into  the  atmosphere. 

If  a  known  volume  of  dry  air  is  forced  through  a  known 
weight  of  lime-water  the  increase  in  weight  of  the  water 
will  be  the  weight  of  carbon  dioxide  in  the  volume  of  air 
used. 

66.  How  Produced. — Carbon   dioxide  is  formed   when 
carbon  or  any  substance  containing  carbon  is  burned  in 
a  plentiful  supply  of  air;   thus  mine  fires,  explosions  of  gas, 
burning  of  lamps  and  explosions  of  powder  are  the  prin- 
cipal producers  of  carbon  dioxide  by  combustion  in  mines. 
It  is   also  produced   when  vegetable  and   animal  matter 
decays   and   by  the  breathing  of  men  and  animals.     As 
the  gas  is  very  soluble  in  water  it  is  largely  carried  into  a 
mine  in  this  manner  and  when  the  water  evaporates  the 
gas  escapes.     The  gas  is  incombustible  and  will  not  sup- 
port  combustion.     Animals   die   when   put  into  this  gas. 
The  supply  of  oxygen  is  cut  off  in  a  manner  similar  to 
drowning.     A  small  quantity  of  the  gas  in  the  air  pro- 
duces headache,   and  if  the  quantity    be    increased    suf- 
ficiently death  results  by  suffocation. 

67.  Effect  of  Black  Damp   on  Atmospheres   Contain- 
ing Fire  Damp. — It  has  been  found  by  experiment  that 
atmospheres  containing  only  13  per  cent  of  oxygen  may 
be  explosive  when  enough  methane  is  also  present.     Con- 
sequently the  atmosphere  in  one  part  of  the  mine  may 
contain  black  damp  enough  to  put  out  an  oil  flame  and 
be  non-explosive,  but  farther  on  in  the  mine  where  more 


GASES  75 

methane  is  present  an  electric  spark  or  a  flame  may  cause 
an  explosion. 

68.  Marsh  Gas. — Marsh  gas  (CH4)  is  a  colorless, 
odorless,  tasteless  gas;  it  is  slightly  soluble  in  water.  It 
is  one  of  the  lightest  known  substances,  its  density  being  8. 

It  is  produced  by  the  decay  of  vegetable  matter  con- 
fined under  water  in  the  absence  of  air.  It  is  found  to  a 
greater  or  less  extent  in  all  coal  seams,  and  when  mixed 
with  air  in  the  following  proportions  forms  fire  damp. 

NOTE. — Marsh  gas  is  also  known  as  methane  or  light 
carbureted  hydrogen;  either  term  may  be  used  when  re- 
ferring to  the  gas. 

Lowest  explosive  limit: 

Volume  of  marsh  gas  =  1 
Volume  of  air  =5.5 


6.5 

Percentage  of  gas  in  mixture  ^—  XI 00  =  15.38  per  cent. 

o .  o 

Greatest  explosive  force: 

Volume  of  marsh  gas  =   1 
Volume  of  air  =9.5 


10.5 

Percentage  of  gas  in  mixture  T7— =  X 100  =  9 . 52  per  cent. 

1U .  o 

Highest  explosive  limit : 


Volume  of  marsh  gas  =   1 
Volume  of  air  =  13 

14 


Percentage  of  gas  in  mixture  ^X 100  =  7. 14  per  cent. 


76  MINING  AND  MINE  VENTILATION 

On  account  of  its  low  density  marsh  gas  diffuses  very 
rapidly  with  air,  forming  fire  damp.  This  mixture,  owing 
to  its  lightness,  ascends  and  lodges  along  the  roof  of  the 
mine. 

Some  idea  of  the  enormous  quantity  of  marsh  gas  that 
may  be  carried  from  a  mine  by  the  ventilating  current 
is  shown  by  the  following  statement:  In  the  main  return 
airway  of  a  certain  mine  is  passing  150,000  cu.ft.  of  air  per 
minute;  this  air  contains  1  per  cent  of  marsh  gas,  hence 
the  total  amount  of  gas  expelled  from  the  mine  in  24 
hours  is  150,000 X 60 X 24 X. 01  =2, 160,000  cu.ft. 

An  explosive  mixture  of  marsh  gas  (or  methane)  and 
air  ignites  if  heated  to  a  temperature  of  about  1300°  F. 
If  the  flame  be  cooled  below  this  temperature  it  goes  out. 

Sulphureted  hydrogen  when  mixed  with  the  quantity 
of  air  necessary  for  complete  combustion  will  ignite  at  a 
temperature  of  about  600  degrees  Fahrenheit,  while  ethane, 
ethylene  and  carbon  monoxide  will,  under  the  same  con- 
ditions, ignite  at  about  1300  degrees  Fahrenheit. 

The  relative  humidity  of  the  mine  air  will  affect  the 
explosive  limits  of  marsh  gas  and  air,  thus  a  percentage 
of  marsh  gas  that  would  just  make  under-saturated  air 
explosive  would  be  totally  inexplosive  in  air  saturated 
with  watery  vapor.  It  has  also  been  found  by  experi- 
ment that  a  mixture  of  marsh  gas  and  air  that  is  outside 
the  explosive  limits  is  rendered  explosive  by  an  increase  of 
pressure.  A  heavy  blast  in  a  mine  might  create  sufficient 
pressure  to  render  an  inexplosive  mixture  explosive. 

69.  Detection  of  Fire  Damp. — Fire  damp  is  detected 
by  means  of  the  safety-lamp.  The  lamp  should  be  raised 
cautiously  in  a  vertical  position  to  the  place  where  gas 
is  suspected.  Some  prefer  testing  with  the  ordinary  work- 
ing flame,  while  others  prefer  a  much  smaller  light.  If 
gas  be  present  it  will  flame  inside  the  gauze.  If  it  is  desired 


GASES 


77 


to  test  for  a  small  percentage  of  gas  in  the  atmosphere 
the  wick  must  be  pulled  down  until  a  very  small  light 
appears  above  the  burner.  In  this  case  the  presence  of 
gas  is  manifested  by  a  non-luminous  cap  above  the  flame. 

When  a  Davy  lamp  burning  sperm  or  lard  oil  is  em- 
ployed the  height  of  the  cap  produced  in  any  percentage 
of  gas  will  vary  slightly,  depending  on  the  original  flame 
used.  The  results  obtained  will  be  more  uniform  if  the 
wick  is  drawn  down  until  a  very  small  light  remains.  The 
percentage  of  gas  in  the  atmosphere  can  then  be  calculated 
as  follows  : 

P  =  percentage  of  gas  in  the  air; 
h  =  height  of  gas  cap  in  inches; 


Thus,  if  the  lamp  indicated  \  inch  cap  the  percentage 
of  gas  present  is 

=  2.6  per  cent  of  gas. 


—  1.25  ins. 

—  .8     " 

—  .6     " 

—  .5     " 


78  MINING  AND  MINE  VENTILATION 

NOTE.— By  experiments  conducted  by  Mr.  Beard  he 
discovered  that  in  an  unbonneted  Davy  lamp  the  height  of 
the  flame  cap  was  1/36  of  the  cube  of  the  percentage  of 
gas  producing  the  cap. 

70.  Ethane. — Ethane  (C2H6)  is  a  member  of  the  marsh- 
gas   series.     It   is   a   colorless,   odorless   and   tasteless   gas 
with  properties  very  similar  to  those  of  marsh  gas;  it  is 
rarely  found  in  mines. 

It  is  produced  by  dry  decomposition  of  vegetable 
matter,  and  is  explosive  when  mixed  with  air. 

71.  Ethylene. — Ethylene    (C2H4),  or    olefiant    gas,    is 
formed  by  the  destructive  distillation  of  wood  and  coal. 
It  is  a  colorless  gas  and  has  a  pleasant  odor.     It  burns 
with  a  bright  yellow  flame  and  is  one  of  the  illuminating 
constituents  of  coal  gas. 

72.  Sulphurated      Hydrogen. — Sulphureted      hydrogen 
(H2S)   is  seldom  found  in  mines  in  large  quantities.     It 
is  a  colorless  gas  and  has  an  odor  of  rotten  eggs.     It  is 
poisonous.     When  breathed  in  small  quantities  produces 
headache  and  larger  quantities  renders  one  unconscious. 
It  explodes  violently  when  mixed  with  air  to  about  seven 
times  its  volume.     The  gas  is  soluble  in  water — one  volume 
of  water  dissolving  about  three  volumes  of  the  gas  at  ordi- 
nary temperature  and  pressure. 

A  familiar  example  of  the  action  of  this  gas  is  seen 
in  its  effect  upon  silver,  which  becomes  covered  by  a  bluish- 
black  deposit  after  being  exposed  for  a  short  time  to  air 
containing  the  gas. 

The  gas  occurs  in  the  waters  of  sulphur  springs;  it 
is  often  found  in  the  air  in  sewers  and  is  produced  by  the 
decay  of  organic  matter  containing  sulphur. 


GASES 


79 


TABLE  I 

SAMPLES   OF   MINE   AIR   EXAMINED   AND   RESULTS   OF 
THE   EXAMINATION 


State. 

County. 

Kind  of  Coal. 

Volume  of 
Air  Current, 
Cu.ft.  per 
Min. 

CO2in 
Sample, 
per  Cent. 

CH4  in 

Sample, 
perCent. 

Pennsylvania 

Luzerne 

Anthracite 

18,100 

0.07 

1.34 

1  < 

'  ' 

<  i 

18,100 

.07 

1.34 

« 

" 

'« 

25,760 

.07 

1.16 

" 

" 

" 

178,560 

.0-3 

.76 

<  < 

" 

" 

178,560 

.09 

.78 

" 

11 

tl 

90,000 

.06 

1.01 

" 

" 

" 

90,000 

.05 

1.04 

" 

11 

" 

140,344 

.08 

.35 

" 

" 

Anthracite 

140,344 

.08 

.37 

" 

11 

" 

(a) 

.04 

.02 

" 

" 

11 

(a) 

.05 

.04 

" 

" 

<  < 

(a) 

.05 

2.34 

" 

11 

" 

(a) 

.07 

2.37 

" 

H 

" 

44,200 

.04 

1.57 

" 

11 

" 

44,200 

.02 

1.60 

" 

Lackawanna 

" 

28,764 

.33 

.52 

<  t 

11 

1  1 

28,764 

.30 

.50 

" 

" 

" 

21,000 

.28 

.76 

" 

" 

11 

21,000 

.27 

.75 

" 

Luzerne 

" 

17,136 

.13 

1.27 

" 

" 

11 

17,136 

.10 

1.27 

" 

" 

'< 

60,060 

.16 

2.29 

" 

14 

'* 

23,760 

.14 

2.20 

'  ' 

M 

'  ' 

23,760 

.13 

2.19 

lt 

11 

" 

13,600 

.17 

3.06 

'  ' 

<  < 

<  < 

13,600 

.16 

3.05 

1  ' 

Williamson 

Bituminous 

36,190 

.24 

.14 

1  ( 

H 

" 

41,580 

.35 

.21 

'  f 

'  ' 

'  ' 

54,225 

.05 

.09 

" 

" 

" 

16,240 

.37 

.21 

1  1 

'  ' 

'  ' 

13,650 

.44 

.19 

t( 

" 

<  < 

23,870 

.05 

.00 

t  < 

Jackson 

<  < 

30,800 

.05 

.02 

(a)  Still  air. 


80  MINING  AND  MINE  VENTILATION 

TABLE  I — Continued 


Volume  of 

COa  in 

CH4  in 

State. 

County. 

Kind  of  Coal. 

Air  Current, 
Cu.ft.  per 

Min. 

Sample 
perCent. 

Sample, 
per  Cent 

Pennsylvania 

Jackson 

Bituminous 

55,300 

.11 

.04 

<  < 

«  < 

20,844 

.31 

.00 

t  t 

Franklin 

90,396 

.05 

.03 

1  1 

64,288 

.10 

.24 

'  l 

6,000 

.10 

.35 

Colorado 

Fremont 

(a) 

.19 

.34 

1  1 

(a) 

.29 

.41 

i  ( 

27,090 

.05 

.21 

West  Virginia 

14,000 

.05 

.88 

(a)  Still  air. 
QUESTIONS 

1.  What  is  calcium  carbide? 

2.  How  is  it  made  and  for  what  is  it  used? 

3.  How  should  it  be  stored? 

4.  What  is  acetylene  gas? 

5.  Describe  the  acetylene  flame. 

6.  What  precautions  should  be  observed  in  using  acety- 
lene gas  as  an  illuminant  in  the  mine? 

7.  What  is  the  formula  for  acetylene  gas? 

8.  What  is  the  specific  gravity  of  acetylene  gas? 

9.  Does   the   flame   from   an   acetylene   lamp   give    off 
smoke? 

10.  What  are  the  dangers  to  be  met  with  in  the  use 
of  acetylene  lamps  in  the  mine? 

11.  What  is  meant  by  the  term  "  occluded  gases  "? 

12.  What  are  the  physical  properties  of  air? 

13.  What  is  the  chemical  formula  for  air? 

14.  How  is  carbon  monoxide  produced? 

15.  How  may  carbon  monoxide  be  changed  to  carbon 
dioxide? 


GASES  81 

16.  How  is  carbon  dioxide  produced  and  what  is  its 
density? 

17.  Where  is  carbon  dioxide  usually  found?     Why? 

18.  How  is  marsh  gas  produced?     (a)  What  is  its  den- 
sity?    (6)  What  is  its  chemical  formula? 

19.  What  is  fire  damp? 

20.  What  per  cent  of  gas  is  in  the  mine  atmosphere 
when  it  is  (a)  at  its  lowest  explosive  limit?     (6)  Highest 
explosive  limit?     (c)   When  the  mixture  is  such  that  the 
explosive  force  is  greatest? 

21.  What  effect  has  the  relative  humidity  of  the  atmos- 
phere on  the  explosive  limits  of  fire  damp? 

22.  How  is  fire  damp  detected? 

23.  If  a  cap  of  one  inch  appeared  on  your  safety  lamp, 
what  is  the  per  cent  of  gas  in  the  atmosphere? 

24.  What  is  the  formula  and  density  of  ethane?     How 
is  it  produced? 

25.  What  is  the  density  of  sulphur eted  hydrogen  and 
how  is  it  produced? 

26.  If  CO  gas  is  passing  over  a  fire  how  may  it  be  reduced 
to  CO2? 

27.  An    ordinary    wick-fed    flame   goes    out   when    the 
proportion  of  oxygen  in  mine  air  is  reduced  to  about  17 
per  cent.     Will  an  acetylene  flame  burn  in  this  percentage 
of  oxygen? 

28.  What  is  changed  when  a  gas  is  compressed?    the 
size  of  the  molecules  or  the  distance  between  them? 

29.  How  much  must  the  volume  of  air  in  a  pneumatic 
drilling  hammer  be  compressed  to  drive  it  at  a  pressure 
of  45  Ibs.  per  square  inch? 

30.  How  deep  must  water  be  in  a  vessel  so  that  its  press- 
ure upon  the  bottom  may  be  the  same  as  that  of  the  atmos- 
phere? 


CHAPTER  X 
SPECIFIC  HEAT 

73.  By   specific   heat   is   meant   the   quantity   of   heat 
necessary   to   raise   the   temperature   of   a   substance   one 
degree  compared  with  the  amount  of  heat  necessary  to 
raise  the  temperature  of  an  equal  weight  of  water  one 
degree. 

Place  1  Ib.  of  shot  in  one  test  tube,  and  1  Ib.  of  iron 
filings  in  another  similar  tube.  Raise  both  to  the  same 
temperature  by  placing  them  in  a  vessel  of  hot  water. 
Into  each  tube  pour  equal  weights  of  water  that  has  been 
cooled  to  32°  F.  by  means  of  ice.  Take  the  temperature 
of  the  water  in  each  and  it  will  be  found  that  the  filings 
have  given  the  water  the  greater  amount  of  heat,  as  is  shown 
by  the  higher  temperature  of  the  water  in  the  tube  con- 
taining the  filings. 

This  experiment  shows  that  iron  has  a  greater  amount 
of  heat  than  lead  at  the  same  temperature. 

74.  Heat  Capacity. — If  equal  weights  of  water,  iron  and 
mercury  are  so  placed  that  each  will  receive  as  many  heat 
units  per  minute  as  the  other,  at  the  end  of  a  given  time  a 
thermometer  will  show  that  the  mercury  has  been  warmed 
through  about  30  times  and  the  iron  about  9  times  as 
many   degrees   as   the   water.     This   shows   that   a   given 
weight  of  mercury  requires  about  ^V  and  an  equal  weight  of 
iron  i  as  much   heat   to*  warm  it  one  degree  as  an  equal 
weight  of  water  requires;    therefore  all   substances  do  not 
have  the  same  heat  capacity. 

82 


SPECIFIC  HEAT  83 

Water  being  the  standard  the  heat  capacity  of  all  sub- 
stances are  compared  with  its  heat  capacity,  from  which 
we  get  a  set  of  ratios  known  as  specific  heats. 

The  following  table  gives  the  average  specific  heat  of 
the  most  common  substances,  water  being  the  standard: 

TABLE    OF   SPECIFIC    HEAT 

Air  (at  constant  pressure) 0 . 237 

Water. 1.000 

Alcohol 0.620 

Copper 0.094 

Iron 0.113 

Lead 0.031 

Mercury 0.033 

Silver 0.056 

Ice 0.502 

Steam 0.480 

Aluminum 0 . 214 

Tin 0.055 

Zinc 0.094 

Hydrogen  (at  constant  pressure) ......  3.406 

75.  Measurement  of  Specific  Heat. — A  convenient 
method  of  measuring  the  specific  heat  of  a  body  is  the 
METHOD  OF  MIXTURE.  W'hen  two  bodies  that  are  at  differ- 
ent temperatures  are  put  together  the  temperature  of  one 
will  fall  and  that  of  the  other  will  rise  until  they  reach 
the  same  temperature.  It  will  also  be  noticed  that  the 
heat  absorbed  by  the  cool  body  in  heating  is  exactly  the 
amount  given  out  by  the  hot  body  in  cooling.  This  prin- 
ciple may  be  stated  in  its  simplest  form  as  follows: 

HEAT  GAINED  =  HEAT  LOST.  The  quantity  of  heat 
absorbed  by  the  cool  body  in  heating  =  mass  X  change  in 
temperature  X  specific  heat. 


84  MINING  AND  MINE  VENTILATION 

The  quantity  of  heat  given  out  by  the  hot  body  in 
cooling  =  mass  X  change  in  temperature  X  specific  heat. 
Thus, 


t  =  temperature  change; 
s  =  specific  heat; 


EXAMPLE.  —  Two  pounds  of  fine  shot  at  90°  were  poured 
into  1  Ib.  of  water  at  15°,  and  the  resulting  temperature 
was  20°.  What  is  the  specific  heat  of  the  shot? 

Since  the  specific  heat  of  water  =  1 


=  2X70Xs; 
therefore, 

s  =  r-7  =  .036—  ,  specific  heat  of  the  shot. 


If  the  same  quantity  of  heat  is  im  parted  to  equal  weights 
of  water  and  fine  shot  the  temperature  of  the  shot  will 
be  about  28  times  higher  than  that  of  the  water: 

Specific  heat  of  water  _L__oc_ 

Specific  heat  of  shot  .036 

With  the  exception  of  the  gas  hydrogen,  water  has  the 
highest  heat  capacity  —  that  is,  the  largest  specific  heat  of 
all  substances. 

On  this  account  water  is  well  suited  for  conveying 
heat  in  the  warming  of  buildings.  For  a  similar  reason 
the  presence  of  a  large  quantity  of  water  prevents  a  rapid 
change  in  the  temperature  of  the  air  in  contact  with  it, 
hence  large  bodies  of  water  moderate  the  climate  in  their 
vicinity. 


SPECIFIC  HEAT  85 


QUESTIONS 

1.  When    two    liquids    having    different    temperatures 
are  mixed,  what  is  the  relation  between  the  quantity  of 
heat  lost  by  the  warmer  and  the  quantity  of  heat  gained 
by  the  cooler  liquid? 

2.  What  is  the  meaning  of  specific  heat? 

3.  If  12  Ibs.  of  water  at  16°  F.  and  72  Ibs.  of  metal 
at  100°  F.  when  mixed  give  a  final  temperature  of  30°  F., 
find  the  specific  heat  of  the  metal. 

4.  A  piece  of  nickel  at  100°  F.  was  dropped  into  an 
equal  weight  of  water  at  32°  F.  and  the  resulting  temper- 
ature was  10°.     Find  the  specific  heat  of  the  nickel. 

5.  If  an  equal  weight  of  water  and  iron  at  the  same 
temperature  be  so  placed  that  each  receive  the  same  amount 
of  heat  per  minute,  after  five  minutes  which  will  be  the 
higher  in  temperature? 

6.  What  substance  is  used  as  the  standard  for  comput- 
ing specific  heat? 

7.  The  specific  heat  of  iron  is  higher  than  lead.     How 
would  you  prove  this  statement? 

8.  If  equal  masses  of  water,  iron  and  lead  are  so  placed 
that  each  receive  the  same  number  of  heat  units  per  min- 
ute,   (a)    which   will  show   the   highest  temperature?     (6) 
the  lowest? 

9.  Why  is  water  well  suited  for  conveying  heat  in  the 
warming  of  buildings? 

10.  Would    alcohol    be   a   better   heat    conveyor   than 
water?     Why? 

11.  A  piece  of  silver  at  194°  F.  weighing  200  ozs.  is  put 
into  a  volume   of  water  at  a  temperature  of  50°  F.     If 
the  resulting  temperature  is  64.76°  F.,  what  is  the  weight 
of  the  water? 


86  MINING  AND  MINE  VENTILATION 

Sp.ht.  X mass  X  temperature  change  = 

sp.ht.X  mass  X  temp,  change 
Therefore, 

(.056X200)  X  (194-64.76)  -f-  (1  X64.76-50)  = 

98  ozs.,  wt.  of  water. 


CHAPTER  XI 
MINE  VENTILATION 

76.  Ventilation. — The  movement  of  air  through  a 
mine  is  caused  by  a  difference  in  pressure  between  the 
intake  and  return  airways.  The  velocity  at  which  the 
air  moves  and  the  quantity  of  air  passing  through  the 
airways  of  a  mine  will  depend  on  this  difference  in  pressure 
together  with  the  resistance  offered  to  the  movement 
of  the  air  by  the  rubbing  surface  of  the  airways. 

The  most  important  point  to  be  considered  in  con- 
nection with  mine  ventilation,  after  the  proper  quantity 
of  air  has  been  decided  upon,  is  the  determination  of  the 
mine  resistance  or  the  pressure  that  will  be  necessary 
to  overcome  the  resistance  offered  by  the  mine. 

A  mistake  is  frequently  made  by  installing  a  fan  designed 
to  deliver  a  large  quantity  of  air  at  a  water  gauge  insuffi- 
cient to  overcome  the  resistance  of  the  mine.  A  fan  having 
certain  dimensions,  producing  a  2-in.  water  gauge,  may 
at  one  mine  cause  to  be  circulated  100,000  cu.ft  of  air, 
while  at  another  mine  the  same  fan  would  produce  only 
50,000  cu.ft.  of  air  with  the  same  water  gauge,  namely, 
2  ins. 

The  general  impression  among  mining  students  is  that 
the  water  gauge  generated  at  a  fan  is  due  to  the  mine 
resistance;  this  is  not  true;  the  fan  produces  the  water 
gauge  and  the  mine  resistance  consumes  it  or  that  part 
of  it  which  is  necessary  to  overcome  the  friction  offered 
by  the  mine. 

87 


88  MINING  AND  MINE  VENTILATION 

It  does  not  matter  whether  a  fan  is  ventilating  a  mine 
or  running  in  the  open  atmosphere,  the  water  gauge  will 
be  the  same  in  both  cases  if  the  revolutions  remain  the 
same. 

A  fan  designed  to  produce  50,000  cu.ft.  of  air  with 
a  1-inch  water  gauge  might  be  placed  at  a  mine,  the 
airways  in  which  may  be  of  ample  size  and  yet  the  quan- 
tity of  air  might  be  less  than  one-half  the  volume  expected. 
This  is  due  to  the  fact  that  the  water  gauge  produced  by 
the  fan  is  not  sufficient  to  overcome  the  mine  resistance 
and  produce  sufficient  velocity.  Therefore  it  will  readily 
be  seen  that  in  order  to  cause  air  to  move  through  this 
mine  at  a  greater  velocity  the  water  gauge  or  pressure 
must  be  increased;  this  can  only  be  done  by  the  fan  or 
other  means  employed  for  the  purpose  of  producing  venti- 
lation. 

77.  Pressure  Defined. — Air  in  motion  in  a  mine  is 
under  the  influence  of  three  distinct  pressures,  namely, 
the  VELOCITY,  STATIC  and  DYNAMIC  or  TOTAL  PRESSURES. 

The  VELOCITY  PRESSURE  is  that  pressure  which  is 
required  to  create  the  velocity  of  flow. 

The  STATIC  PRESSURE,  sometimes  termed  the  FRIC- 
TIONAL  PRESSURE,  is  that  pressure  required  to  overcome 
the  resistance  offered  to  the  flow. 

The  TOTAL  PRESSURE,  also  termed  the  DYNAMIC  or 
IMPACT  PRESSURE,  is  the  sum  of  the  static  and  velocity 
pressures. 

QUESTION. — The  water  gauge  produced  by  a  fan  is 
^  in.,  the  airway  is  5  ft.  by  5  ft.  What  must  be  the  rub- 
bing surface  in  this  mine  to  prevent  the  air  from  moving 
faster  than  1  ft.  per  minute? 

Solution. 

-&  or 


MINE  VENTILATION     .  89 

NOTE. — See  Chapter  XIII,  for  formulas  and  values  for  k, 
which  is  the  coefficient  of  friction. 

It  is  plain  that  in  order  to  increase  the  velocity  in  this 
mine  it  will  be  necessary  to  erect  a  fan  capable  of  producing 
a  greater  water  gauge,  because  in  this  case  nearly  the 
entire  water  gauge  generated  by  the  fan  is  consumed  in 
overcoming  the  mine  resistance  and  only  a  small  part  of 
it  is  left  to  produce  a  velocity.  Hence  the  static  pressure 
required  to  overcome  the  resistance  of  the  mine  in  ques- 
tion is  equal  to  about  J-in.  water  gauge,  and  any  addi- 
tional pressure  that  might  be  added  will  be  wholly 
consumed  in  producing  velocity  and  overcoming  the 
additional  friction  caused  by  the  increased  velocity. 

The  static  water  gauge  or  pressure  can  be  found  by  the 
use  of  two  water  gauges,  one  of  which  should  be  piped 
into  the  airway  with  the  end  of  the  pipe  opening  at  right 
angles  to  the  direction  of  the  air  current,  and  the  other 
gauge  close  to  the  same  place  with  the  end  of  the  pipe 
opening  pointing  against  the  current  so  that  the  air  can 
rush  into  the  end  of  the  pipe.  While  the  gauges  are 
in  this  position  it  will  be  noticed  that  one  of  the  gauges 
will  show  a  higher  reading  than  the  other.  The  difference 
in  the  readings  is  the  velocity  pressure,  or  the  pressure 
producing  the  velocity. 

WATER  GAUGE. — The  water  gauge,  Fig.  13,  consists 
of  a  glass  tube  bent  in  the  form  of  a  U,  both  ends  of  which 
are  open.  When  it  is  desired  to  measure  the  difference 
of  pressure  between  two  airways,  one  of  the  ends  is  inserted 
in  a  small  hole  bored  in  a  door  or  brattice  between  the 
intake  and  return  airways.  When  in  this  position  the 
two  ends  of  the  gauge  are  subjected  to  two  different  press- 
ures, the  atmospheric  pressure  on  the  intake  side  if  the  fan 
is  exhausting,  and  a  pressure  less  than  the  atmosphere 
on  the  return  side.  This  difference  in  pressure  causes  the 


90 


MINING  AND  MINE  VENTILATION 


water  to  drop  in  the  tube  on  one  side  of  the  gauge  and  to 
rise  a  corresponding  distance  on  the  other  side.  The 
difference  of  the  level  of  the  water  in  the  two  tubes  can 
be  read  by  means  of  the  scale  attached,  as  shown  in  the 
figure. 


FIG.  14. 


FIG.  13. 

ANEMOMETER. — The  anemometer,  Fig.  14,  is  an  instru- 
ment used  for  measuring  the  velocity  of  air  currents  in 
mines  and  the  ventilators  of  public  buildings.  The  instru- 
ment consists  of  a  delicately  constructed  fan  wheel  which 
revolves  in  a  circular  frame.  Placed  in  an  air  passage 
the  instrument  registers  automatically  the  rate  at  which 


MINE  VENTILATION  91 

the  air  is  traveling  through  it.  The  revolutions  of  the 
wheel  are  recorded  by  means  of  several  pointers  or  hands 
on  the  face  of  the  instrument.  The  large  hand  makes 
one  revolution  for  each  hundred  revolutions  of  the  wheel. 
One  revolution  of  the  large  hand  per  minute  is  equivalent 
to  a  velocity  of  100  ft.  per  minute.  ' 

Anemometers  indicate  satisfactorily  velocities  up  to 
10,000  ft.  per  minute,  and  each  instrument  is  supplied 
with  a  chart  of  correction  for  different  velocities. 

78.  Calculations. — The  relation  between  fan  speed, 
pressure,  volume  of  air  delivered  and  power  required  have 
been  fully  verified  by  tests  and  will  be  found  convenient 
for  reference  by  those  interested  in  mine  ventilation. 

1.  The  volume  of  air  delivered  by  a  fan  varies  directly 
as   the   number   of   revolutions,    resistance   remaining   the 
same;   that  is,  if  a  fan  running  80  R.P.M.  delivers  100,000 
cu.ft.,  how  much  air  will  be  delivered  if  the  revolutions 
are  increased  to  160? 

Solution.— 80  :  160::  100,000  :  X  X  =  200,000  cu.ft. 

2.  The  water   gauge  or   pressure    produced  by  a  fan 
varies  directly  as  the  square  of  the  speed.     If  a  fan  run- 
ning at  80  R.P.M.  produces  1  in.  water  gauge,  what  water 
gauge  will  be  produced   if  the  revolutions  are  increased 
to  160? 

Solution.— 802  :  1602 ::  1  in.  :  X.     X  =  4  in.  w.g. 

3.  The  water  gauge  or  pressure  required  to  force  air 
through  a  mine  varies  directly  as  the  square  of  the  volumes. 
If  with  1  in.  water  gauge  100,000  cu.ft  of  air  are  passing 
through   a  mine  per  minute,   what  water  gauge  will   be 
required  to  pass  200,000  cu.ft.  per  minute? 

Solution.— 100,0002  :  200,0002::  1  :  X.    X  =  4  in.  w.g. 


92  MINING  AND  MINE  VENTILATION 

4.  The  power  required  to  drive  a  fan  varies  directly 
as  the   cube   of  the  revolutions.     If  it  requires  25   H.P. 
to  run  a  fan  80  R.P.M.,  what  power  will  be  required  to  run 
the  fan  160  R.P.M.? 

Solution.— 803  :  1603 : :  25  :  X.     X  =  200  H.P. 

5.  The  power  required  to  ventilate  a  mine  varies  as 
the  cube  of  the  volume  of  air  passing.     If  it  requires  25 
H.P.   to  circulate   100,000  cu.ft.   of  air  through   a  mine, 
what  H.P.  will  be  required  to  circulate  200,000  cu.ft.? 

Solution.— 100,0003  :  200,0003  ::25  :  X.     Z  =  200  H.P. 

6.  To  find  the  size  of  motor  or  engine  required  to  drive 
a  fan  under  average  mine  conditions,  multiply  the  number 
of  cubic  feet  of  air  by  the  water  gauge  and  divide  this 
product   by  4500.     If   a  fan  is   delivering   100,000   cu.ft. 
of  air  at  2  in.  water  gauge,  what  size  motor  or  engine  will 
be  required  to  drive  it? 


„  ,   ..          100,000X2          .  „„ 
Solution. r —  =44.4  H.P. 


NOTE. — The  above  formula  bases  the  equipment  at 
71  per  cent  mechanical  efficiency,  or,  which  is  the  same 
thing : 

100,000X2X5.2 


33,000  X. 71 


=  44.4  H.P.  nearly. 


7.  The  horse-power  of  an  engine  is  found    by  means 
of  the  following  formula: 


MINE  VENTILATION  93 

PXLXAXN 


33,000 


=  H.P. 


P  =  mean  effective  pressure; 

L  =  length  of  stroke  in  feet; 

A  =  area  of  piston  in  square  inches  ; 

N  =  number  of  strokes  per  minute. 

EXAMPLE.  —  If  a  16  in.  by  18  in.  engine  is  running  150 
R.P.M.  and  the  mean  effective  pressure  is  40  Ibs.,  what  is 
the  H.P.? 

NOTE.  —  The  number  of  revolutions  at  which  an  engine 
runs  per  minute  multiplied  by  2  will  equal  the  number 
of  strokes. 

40X1^X201X300     irkft  ~  TJ  o 
Solution.—  330QO        -=  109.6  H.P. 

8.  The  electric  H.P.  consumed  by  a  direct-current 
motor  is  found  by  means  of  the  following  formula: 

VXA 


V  =  volts; 
A  =  amperes; 
746  =  number  of  watts  in  one  H.P. 

EXAMPLE.  —  If  a  direct-current  motor  is  using  100 
amperes,  250  volts,  what  is  the  H.P.  input? 

Solution.—  10°*25°  =  33.5  H.P. 
74o 

9.  The  mechanical  efficiency  of  a  ventilating  equip- 
ment is  the  ratio  of  the  actual  H.P.  consumed  to  the  actual 
H.P.  applied. 


94  MINING  AND  MINE  VENTILATION 

EXAMPLE.  —  If  the  actual  H.P.  of  an  engine  is  44.4 
and  the  effective  H.P.  is  31.5,  what  is  the  mechanical 
efficiency? 

31  5 
Solution.  —  ~rr~  =  71%.  nearly. 


10.  The  theoretical  water  gauge  of  a  fan  is  computed 
by  means  of  the  following  formula: 


32.16X5.2' 

V  =  peripheral  speed  of  fan  in  feet  per  second ; 
.078  =  weight  of  a  cubic  foot  of  air; 
32.16  =  g.  acceleration  due  to  gravity; 

5. 2  =  pressure  per  square  foot  for  1  in.  water  gauge. 

EXAMPLE. — If  a  fan  is  running  80J  ft.  peripheral  speed 
per  second,  what  is  the  theoretical  water  gauge? 

80FX.078 
Solution.— 32  1       5  2  =  3+ms.  water  gauge. 

11.  The  manometric  efficiency  of  a  fan  is  the  ratio 
of  the  theoretical  water  gauge  to, the  actual  water  gauge 
developed  by  the  fan. 

EXAMPLE. — If  a  fan  running  at  a  peripheral  speed 
of  80J  ft.  per  second  produces  an  actual  water  gauge  of 
2  ins.  and  the  theoretical  water  gauge  is  3  ins.,  as  found 
in  Example  10,  what  is  the  manometric  efficiency  of  the 
fan? 

2" 
Solution. — 577  =  66f  per  cent  manometric  efficiency. 

o 


MINE  VENTILATION  95 

12.  The  volumetric  capacity  of  a  fan  is  the  ratio  of 
the  actual  volume  produced  to  the  cubical  contents  of  the 
fan  multiplied  by  the  number  of  revolutions. 

EXAMPLE. — The  cubical  contents  of  a  fan  10  ft.  in 
diameter  and  5  ft.  wide  is  392.7  cu.ft  and  running  at  100 
R.P.M.  =  39,270  cu.ft.  If  the  actual  volume  delivered 
by  the  fan  is  78,540,  what  is  its  volumetric  capacity? 

Solution. —     *0 _   =200  per  cent. 

€>u  )£  I  U 

EXAMPLE.— The  quantity  of  air  delivered  by  a  fan  is 
150,000  cubic  feet  per  minute  at  a  water  gauge  of  3i  inches. 
If  the  efficiency  of  the  plant  is  65  per  cent  and  the  average 
steam  pressure  on  the  piston  is  45  Ibs.  per  square  inch, 
what  size  engine  will  be  required  to  do  the  work  ? 

Solution. — The  foot  pounds  of  work  done  on  the  air  per 
minute  are  150,000X3.25X5.2  =  2,535,000. 

The  efficiency  of  the  engine  being  65  per  cent,  the  foot 
pounds  developed  by  the  engine  must  be 

2,535,000  X 100  = 
uo 

The  foot  pounds  developed  by  the  engine  are,  piston  speed 
in  feet  per  minute  X  pressure  per  square  inch  on  piston 
X  area  of  piston.  So  that,  taking  the  piston  speed  to 
average  400  feet  per  minute,  the  area  of  the  piston  is 


150,000  X  3.25  X  5.2  X 100  _16 
65  X  400  X  45  X. 7854 

79.  The    ventilating    pressure    may    be    expressed    in 
inches  of  water  gauge  or  in  pounds  per  square  foot.     For 


96  MINING  AND  MINE  VENTILATION 

instance,  a  water  gauge  of  2  ins.  is  equal  to  2X5.2  or  10.4 
Ibs.  per  square  foot.  Should  it  be  necessary  to  express 
the  pressure  per  square  foot  in  inches  of  water  gauge, 
simply  divide  the  pressure  per  square  foot  by  5.2.  The 
number  5.2  is  found  by  dividing  62.5,  the  weight  of  a  cubic 
foot  of  water,  by  12. 

EXAMPLE. — If  the  water  gauge  is  2J  ins.,  (a)  what  is 
the  pressure  per  square  foot?  (6)  If  the  area  of  the  airway 
is  30  sq.ft.,  what  is  the  total  pressure? 

Solution.— (a)  2.5X5.2  =  13  Ibs.  per  sq.ft. 
(6)     SOX  13  =  390  Ibs. 

80.  First  Law  of  Friction. — When  the  velocity  remains 
constant  the  total  pressure  required  to  overcome  friction  varies 
directly  as  the  extent  of  the  rubbing  surface. 

This  law  means  that  if  the  rubbing  surface  be  doubled 
the  pressure  must  also  be  doubled  in  order  to  pass  the  air 
at  the  same  velocity. 

EXAMPLE.— If  an  airway  10  ft.  by  10  ft.  and  1000  ft. 
long  is  increased  in  length  to  2000  ft.,  how  much  addi- 
tional pressure  must  be  added  to  pass  the  same  quantity 
of  air? 

Solution. — As  the  rubbing  surface  is  doubled  the  press- 
ure will  therefore  have  to  be  doubled  in  order  to  pass  the 
same  quantity. 

EXAMPLE. — Find  the  rubbing  surface  of  an  airway, 
the  sides  of  which  are  10  ft.  by  6  ft.  and  2000  ft.  long. 

Solution.— 10+10+6+6  =  32  ft.  distance  around  the  air- 
way. 32  X 2000  =  64,000  sq.ft.  Ans. 

EXAMPLE. — Suppose  in  the  above  example  the  sides 
of  the  airway  were  15  ft.  by  4  ft.,  the  length  being  the 
same,  what  would  be  the  rubbing  surface? 


MINE  VENTILATION  97 

Solution. — 15+15+4+4  =  38  ft.  distance  around  the  air- 
way. 38X2000  =  76,000  sq.ft.  Ans. 

EXAMPLE. — If  20,000  cu.ft.  of  air  passes  per  minute 
through  an  airway  1000  ft.  long,  what  must  be  the  increase 
in  pressure  to  pass  the  same  quantity  through  the  same 
airway  if  the  length  is  increased  to  1500  ft.? 

Solution. — Since  the  rubbing  surface  is  increased  1.5 
times,  it  follows  that,  according  to  the  first  law  of  friction, 
the  pressure  must  also  be  increased  1.5  times. 

The  form  of  the  airway  in  a  mine  has  considerable 
effect  on  the  amount  of  rubbing  surface,  as  will  be  shown 
by  the  following  example: 

EXAMPLE. — Suppose  there  are  three  airways,  the  length 
of  each  1000  ft.;  one  airway  being  8  ft.  by  8  ft.,  another 
4  ft.  by  16  ft.,  the  third  being  circular,  the  diameter  of 
which  is  9.026  ft.,  what  is  the  rubbing  surface  and  area 
of  each? 

Solution. 

1.  (8+8+8+8)  X 1000  =  32,000  sq.ft.  rubbing  surface, 

Area  =  64  sq.ft. 

2.  (4+4+16+16)  X1000  =  40,000  sq.ft.  rubbing  surface, 

Area  =  64  sq.ft. 

3.  9.026X3.1416X1000  =  28,356  sq.ft.  rubbing  surface, 

Area  =  64  sq.ft. 

81.  Second  Law  of  Friction. — When  the  velocity  and 
rubbing  surfaces  remain  the  same,  the  pressure  required  to 
force  air  through  the  airways  of  a  mine  increase  and  decrease 
inversely  as  the  sectional  area  of  the  airways  increase  or  de- 
crease. 


98  MINING  AND  MINE  VENTILATION 

This  law  means  that  if  the  velocity  and  rubbing  surface 
remain  the  same,  the  pressure  per  square  foot  that  will 
be  necessary  to  maintain  this  velocity  will  increase  as  the 
sectional  area  decreases,  and  as  the  sectional  area  increases 
the  pressure  will  decrease. 

Hence  if  the  sectional  area  be  reduced  to  J,  J,  etc., 
of  its  original  area,  the  pressure  per  square  foot  must  be 
increased  2,  4,  etc.,  times  in  order  to  maintain  the  same 
velocity,  and  if  the  sectional  area  be  increased  2,  4,  etc., 
times  the  pressure  per  square  foot  necessary  to  main- 
tain the  same  velocity  will  be  reduced  to  J,  J,  etc.,  of  the 
original  pressure.  The  rubbing  surface  remaining  the  same. 

EXAMPLE. — If  it  requires  a  pressure  of  10.4  Ibs.  to  main- 
tain a  velocity  of  1000  ft.  per  minute  in  an  airway  8  ft. 
by  8  ft.,  what  pressure  per  square  foot  will  be  required 
to  maintain  the  same  velocity  in  an  airway  4  ft.  by  4  ft. 
rubbing  surface  remaining  the  same? 

Solution.— 8' X  8' =  64  sq.ft.  area. 
4  X4  =16  sq.ft.  area. 

16  :  64::  10.4  :  X,  or  X  =  41.6  Ibs.  per  sq.ft. 

EXAMPLE. — If  it  requires  a  pressure  of  5  Ibs.  per  square 
foot  to  pass  air  through  an  8  ft.  by  10  ft.  airway  with  a 
certain  velocity,  what  pressure  per  square  foot  will  be 
required  to  pass  air  through  a  6  ft.  by  8  ft.  airway  with 
the  same  velocity?  The  rubbing  surface  remaining  the  same. 

EXAMPLE. — If  it  requires  a  pressure  of  2  Ibs.  to  force 
air  through  a  10  ft.  by  10  ft.  airway,  what  pressure  per 
square  foot  will  be  required  to  pass  air  through  an  airway 
5  ft.  by  5  ft.  at  the  same  velocity?  The  rubbing  surface 
remaining  the  same. 


MINE  VENTILATION  99 

82.  Third  Law  of  Friction. — The  pressure  required  to 
overcome  friction  varies  as  the  square  of  the  velocities  or  quan- 
tities when  the  rubbing  surface  and  the  area  of  the  airway 
remain  the  same. 

This  law  means  that  if  the  sectional  area  and  rubbing 
surface  remain  the  same  the  pressure  per  square  foot  will 
vary  as  the  square  of  the  velocity  or  quantity. 

EXAMPLE. — If  it  requires  a  pressure  of  5  Ibs.  to  pro- 
duce a  velocity  of  400  ft.  per  minute  in  a  certain  airway, 
what  pressure  will  be  required  to  produce  a  velocity  of 
500  ft.  in  the  same  airway? 

Solution.— 4002  :  5002::5  :  X,  or  X  =  7.S  Ibs. 

EXAMPLE. — If  10  Ibs.  pressure  produce  a  velocity  350 
ft.  per  minute,  what  pressure  will  be  required  to  produce 
a  velocity  of  700  ft.  per  minute  in  the  same  airway? 

40  Ibs.     Ans. 

TABLE  J 

TABLE  OF  PRESSURE  PER  SQUARE  FOOT  DUE  TO 
DIFFERENT  VELOCITIES  OF  THE  AIR 

Feet  per  Minute.  Pressure  in  Lbs.  per  sq.ft. 

100 006 

150 014 

200 025 

300 057 

400 102 

500 159 

600 230 

700 312 

800 408 

900 517 

1000 ; 638 

1500 1.437 

2000 2.555 

2500..  3.991 


100  MINING  AND  MINE  VENTILATION 

Feet  per  Minute.  Pressure  in  Lbs.  per  sq.ft. 

3000 5.750 

3500 7.825 

4000 10.220 

4500 12.937 

5000 15.970 

5500 19.298 

6000 23.000 

6500... 26.976 

7000 31.302 

7500 35.937 

8000 40.886 

8500 46.155 

9000 51.750 

9500 57.744 

10000 63.883 

FORCE  OF  AIR. — To  ascertain  the  force  in  pounds  per 
square  foot  of  an  air  current,  multiply  the  square  of  the 
velocity  of  the  air  in  feet  per  second  by  .0023. 

QUESTIONS 

1.  What  causes  air  to  move  through  a  mine? 

2.  A  fan  is  running  at  50  revolutions  per  minute,  the 
water  gauge  being  1  in.,  and  is  producing  80,000   cu.ft. 
of  air  at  a  certain  mine;    a  similar  fan  is  in  operation  at 
another  mine  running  at  50  revolutions  and  has  a  water 
gauge  of  1  in.  and  is  producing  only  50,000  cu.ft.  of  air. 
What  is  the  cause  of  the  difference  in  quantity? 

3.  If  the  water  gauge  reading  is  2J  ins.,  what  is  the 
pressure  per  square  foot? 

4.  The  area  of  an  airway  is  60  sq.ft.,  the  water  gauge 
reading  is  2  ins.     What  is  the  total  pressure? 

5.  If  the  water  gauge  reading  at  a  mine  is  1J  ins.  and 
5.2  Ibs.  pressure  per  sq.ft.  are  consumed  in  overcoming  the 
mine  resistance,  what  is  the  velocity? 

6.  Define  static  and  velocity  pressure. 

7.  What  is  the  first  law  of  friction? 


MINE  VEOTllftON  101 

8.  An  airway  is  7£  ft.  high,  12J  ft.  wide  and  5400  ft. 
long.     What  is  the  rubbing  surface? 

9.  Does  the  mine  resistance  or  the  fan   produce  the 
water  gauge? 

10.  A  fan  running  at  50  revolutions  produces  a  water 
gauge  of  1  in.  while  ventilating  a  large  mine.     If  the  mine 
is  cut  off  and  the  fan  allowed  to  run  in  the  open  atmos- 
phere at  the  same  speed,  what  then  will  be  the  water  gauge? 

11.  If  a  fan  running  50  revolutions  per  minute  pro- 
duces 50,000  cu.ft.  of  air  per  minute,  what  quantity  will 
this  fan  produce  when  running  100  revolutions  per  minute? 

12.  If  a  fan  running  at  40  revolutions  per  minute  pro- 
duces a  2-in.  water  gauge,  what  water  gauge  will  be  pro- 
duced when  the  fan  is  running  80  revolutions  per  minute? 

13.  If  a  1-in.  water  gauge  causes  50,000  cu.ft.   of  air 
to  flow  through  a  mine,  what  water  gauge  will  be  necessary 
to  pass  100,000  cu.ft.  of  air  through  the  same  mine? 

14.  If  it  requires  20  H.P.  to  run  a  fan  at  40  revolutions 
per  minute,  what  horse  power  will  be  required  to  run  the 
fan  at  80  revolutions  per  minute? 

15.  If  it  requires  10  H.P.  to  produce  50,000  cu.ft.  of 
air  per  minute,   what  H.P.   will   be  required  to  produce 
100,000  cu.ft.  of  air? 

16.  A  fan  is  delivering  50,000  cu.ft.  of  air  per  minute, 
the  water  gauge  is  1  in.     What  power  motor  or  engine  is 
required  to  do  this  work? 

17.  A  direct-current  motor  is  consuming   100  amperes 
at  a  voltage  of  500.     What  is  the  H.P.? 

18.  If  a  10-ft.  fan  is  running  at   120  revolutions  per 
minute,  what  is  the  theoretical  water  gauge? 

19.  If  the  actual  water  gauge  produced  by  the  fan  in 
Question  18  is  1.3  ins.,  what  is  the  manometric  efficiency? 

20.  If  a  fan  12  ft.  in  diameter  and  5  ft.  wide,  running 
at  100  revolutions  per  minute,  is  delivering  90,000  cu.ft. 


102  •  MINING  AND  MINE  VENTILATION 

of  air  per  minute,  what  is  the  volumetric  capacity  of  the 
fan? 

21.  If  you  were  about  to  order  a  fan  to  ventilate  a 
mine,  what  points  should  be  considered? 

22.  If  a  fan  while  ventilating  a  mine  produces  a  2-in. 
water  gauge,  what  will  be  the  water  gauge  if  the  mine 
is  cut  off  and  the  fan  run  at  the  same  speed  in  the  open 
atmosphere? 

23.  How  is  the  static  pressure  of  a  mine  found? 

24.  If  (in  Question  22)  the  mine  is  cut  off  by  means  of 
a  stopping  so  arranged  and  constructed  that  the  fan  can 
get  no  air,  if  the  revolutions  remain  the  same,  what  will 
be  the  water  gauge? 

25.  If  it  requires  a  pressure  of  10  Ibs.  to  produce  a 
velocity  of  500  ft.   per  minute  in  a  certain  mine,   what 
pressure  will  be  required  to  produce  a  velocity  of  800  ft. 
per  minute? 

26.  If  a  2-in.  water  gauge  produces  a  velocity  of  300 
ft.  per  minute,  what  velocity  will  a  4-in.  water  gauge  pro- 
duce? 

27.  If  it  requires  40  H.P.  to  run  a  fan  80  revolutions 
per  minute,  how  fast  will  the  fan  run  if  50  H.P.  is  applied? 

28.  If   a   fan   running   at    80   revolutions    per   minute 
delivers   100,000  cu.ft.   of  air  per  minute,   at  how  many 
revolutions   per  minute   will   it   have   to   run  to   produce 
200,000  cu.ft  of  air  per  minute? 

29.  If  a  14  in.  by  16  in.  engine  is  running  100  R.P.M. 
and  the  mean  effective  pressure  is  40  Ibs.,  what  is  the  H.P.? 

30.  If  the  effective  horse-power  of  a  ventilating  equip- 
ment is  20.5  and  the  actual  horse-power  is  32,  what  is  the 
mechanical  efficiency? 

31.  If  the  effective  horse-power  of  a  ventilating  equip- 
ment is  40  and  the  pressure  producing  ventilation  is  10  Ib. 
per  square  foot,  what  is  the  quantity? 


MINE  VENTILATION  103 

32.  The  quantity  of  air  delivered  by  a  fan  is  150,000 
cu.ft.   per  minute  and  the  water  gauge  is  2  ins.     What 
is  the  effective  horse-power? 

33.  If  it  requires  27  H.P.  to  produce  50,000  cu.ft.  of 
air  per  minute,  what  quantity  will  64  H.P.  produce? 

34.  If  20   H.P.   will   produce  40,000   cu.ft.   of  air  per 
minute,    what   horse-power   will   be    required    to    produce 
80,000  cu.ft.  per  minute? 

35.  A  fan  is  12  ft.  in  diameter  and  5  ft.  wide;  it  is  run- 
ning  100  revolutions  per  minute;    the  actual  volume  of 
air  delivered  by  this  fan  is  80,000  cu.ft.  per  minute;  what 
is  its  volumetric  capacity? 

36.  A  fan  10  ft.  in  diameter  is  running  100  revolutions 
per  minute.     What  is  the  theoretical  water  gauge? 

37.  If  the  theoretical  water-  gauge  of  "a  fan  is  3  ins. 
and  the  actual  water  gauge  is  2|  ins.,  what  is  the  mano- 
metric  efficiency  of  the  fan? 

38.  There  are  two  airways,  one  of  which  is  6  ft.  by 
6  ft.  and  the  other  4  ft.  by  9  ft.,  each  being  the  same  length, 
namely,   2500  ft.     Through  which  airway  will  the  larger 
quantity  of  air  pass  under  the  same  pressure? 

39.  The  water-gauge  reading  at  a  fan  is  2  ins.     If  the 
static  pressure  at  this  mine  is  8  Ibs.  per  square  foot,  what 
is  the  velocity  pressure? 

40.  The  pressure  produced  by  a  fan  is  .4  of  an  inch 
water  gauge,  the  mine  airway  is  4  ft.  by  4  ft.     What  should 
be  the  length  of  this  airway  in  order  to  prevent  the  air 
moving  faster  than  1  ft.  per  minute? 


CHAPTER  XII 
MINE  VENTILATION 

83.  Mine  Ventilation. — Every  precaution  should  ba 
taken  to  keep  large  airways,  and  a  mine  should  not  be 
permitted  to  get  into  a  condition  requiring  more  than  a 
3-in.  water  gauge  pressure  to  ventilate  it.  However,  a 
great  number  of  old  mines  in  operation  to-day  require 
a  much  larger  gauge,  the  cause  being  due  to  long  airways, 
small  sectional  areas  and  unequal  splitting  of  the  air  cur- 
rent. The  fans  "erected  at.  those  mines  when  the  airways 
were  short  and  little  resistance  offered  to  the  movement  of 
the  air  are  now  unfit  for  the  work  they  are  expected  to 
perform. 

It  is  the  custom  with  some  mine  operators  when  order- 
ing a  fan  to  designate  a  certain  size  fan,  even  making  out 
detailed  specifications  for  it  and  state  that  the  fan  must 
perform  a  certain  work  in  the  number  of  cubic  feet  of  air 
per  minute  and  the  water  gauge  against  which  the  fan 
must  work,  when  as  a  matter  of  fact  the  mine  conditions 
require  an  equipment  entirely  different.  The  want  of 
knowledge  of  such  matters  has  led  many  mine  operators 
into  getting  a  fan  that  does  not  fit  the  mine  conditions. 

The  matter  of  circulating  and  conducting  air  through 
the  workings  of  a  mine  is  a  very  easy  matter  if  in  the  first 
place  a  fan  be  erected  that  will  work  economically  against 
the  mine  conditions. 

VENTILATING  CURRENTS,  How  PRODUCED. — Ventilating 
currents  are  produced  by  natural  heat,  by  water  falling, 
or  a  water-jet,  by  a  steam  jet,  by  a  furnace  and  by  a  fan. 

104 


MINE  VENTILATION 


105 


84.  Natural  Ventilation. — Natural  ventilation  is  pro- 
duced in  a  mine  when  there  is  a  difference  in  elevation 
between  the  intake  and  outlet  airways  and  a  difference 
in  temperature  between  the  two  columns: 

For  the  purpose  of  illustration,  let  Fig.  15  represent 
two  shafts  the  tops  of  which  are  at  different  elevations. 
During  cold  weather  the  shaft  AB  will  be  the  downcast 
because  the  imaginary  column  of  outside  air  from  A  to 


WINTER 

FIG.  15. 


E  is  heavier  than  the  air  column  from  Ct  to  level  of  shaft 
AB,  the  difference  in  weight  being  due  to  the  difference  in 
temperature.  In  the  summer  time  the  outside  air  being 
warmer  than  that  of  the  mine  the  shaft  CD  will  be  the  down- 
cast, and  the  shaft  AB  the  upcast.  This  system  of  ventilation 
works  fairly  well  during  the  seasons  of  extreme  heat  and 
cold,  but  during  the  spring  and  fall  when  the  temperatures 
inside  and  out  are  about  equal,  natural  ventilation  is  inef- 
fective. 


106  MINING  AND  MINE  VENTILATION 

85.  Water   and    Steam   Jet    System   of   Ventilation.— 

This  system  of  ventilation,  while  not  very  successful,  is 
sometimes  applied  in  cases  of  emergency.  The  jet  is  so 
arranged  that  water  is  sprayed  and  allowed  to  fall  down 
the  intake  shaft.  In  connection  with  this  system  a  steam 
jet  is  sometimes  used.  The  steam  jet  is  arranged  so  as  to 
blow  in  the  upcast. 

During  the  year  1852  a  committee  of  the  House  of 
Commons  at  England  reported:  "  That  any  system  of 
ventilation  depending  on  complicated  machinery  is  unde- 
sirable, since  under  any  disarrangement  or  fracture  of  its 
parts  the  ventilation  is  stopped  or  becomes  inefficient. 

"  That  the  two  systems  which  alone  can  be  considered 
as  rival  powers  are  the  furnace  and  the  steam  jet. 

"  Your  committee  is  unanimously  of  opinion  that  the 
steam  jet  is  the  most  powerful  and  at  the  same  time  least 
expensive  method  for  the  ventilation  of  mines.'5 

86.  Furnace  Ventilation. — Furnaces  are  placed  at  the 
bottom  of  the  upcast  and  are  usually  constructed  of  brick 
with  air  chambers  on  either  side  to  prevent  heating  the 
surrounding    strata.     The    heated    air    passing  .  over    the 
furnace  and  entering  the  upcast  is,  by  reason  of  its  rarefied 
state,  lighter  than  the  cool  air  in  the  downcast  shaft  and 
is    consequently    forced    upward.     The    quantity    of    air 
produced  by  a  furnace  depends  principally  on  the  amount 
of  heat  generated  together  with  the  depth  of  the  furnace 
shaft. 

87.  Ventilation    by    Means    of    Fan.— If    a    fan    while 
working  on  a  mine  is  exhausting  air  therefrom,  the  fan 
is  then,  due  to  centrifugal  force,  creating  a  partial  vacuum 
at  its  center  or  axis;    the  extent  of  this  vacuum  depends 
on  the  peripheral  or  rim  speed  of  the  fan.     The  peripheral 
speed  at  which  a  fan  should  run  depends  altogether  on  its 
construction.     While  some  fans  may  stand   a  rim  speed 


MINE  VENTILATION 


107 


of  16,000  ft.  per  minute,  others  will  not  stand  more  than 
5000  ft.  per  minute. 

When  the  inlet  of  the  fan  is  connected  to  the  mine 
the  only  air  that  can  get  to  the  fan  must  pass  through  the 
mine,  and  hence  the  ventilating  current  is  maintained  as 
long  as  the  fan  runs.  When  the  fan  is  running  the  pressure 


A  Robinson  Reversible  Fan. 

of  the  air  is  always  less  at  the  inlet  of  the  fan  than  outside, 
and  the  difference  between  this  pressure  and  the  pressure 
of  the  atmosphere  is  the  pressure  producing  ventilation,  or 
the  extent  to  which  a  vacuum  is  approached  by  the  fan. 

Many  differently  constructed  fans  are  being  used  for 
the  purpose  of  ventilating  mines,  the  most  prominent  of 
which  are  those  manufactured  by  the  Robinson  Ventilat- 


108 


MINING  AND  MINE  VENTILATION 


ing  Company,  American  Blower  Company  (Sirocco), 
Jeffrey  Manufacturing  Company  and  others  possessing 
similar  features. 

THE  ROBINSON  FAN. — The  Robinson  fan,  one  of  the 
late  developments  in  fans  for  mine  ventilation,  Fig.  16, 
shows  the  runner  of  this  fan.  The  blades  are  curved  to 
pass  the  air  through  the  fan  with  the  least  friction  or  loss 
in  power.  By  reason  of  the  blade  arrangement  the  air 


FIG.  16. 

is  readily  changed  from  its  horizontal  direction  as  it  enter? 
the  wheel;  hence,  it  is  claimed,  great  economy  is  obtained 
by  this  fan.  It  is  strongly  constructed  and  is  capable  of 
standing  any  desired  speed. 

The  following  table,  prepared  by  the  Robinson  Ven- 
tilating Company,  shows  the  approximate  quantity  of 
air  delivered  by  their  fan  when  running  at  different  speeds 
and  having  different  dimensions: 


MINE  VENTILATION 


109 


TABLE  K 


Diameter,  Ins. 

Width,  Ins. 

R.P.M. 

Volume. 

18 

17 

2500 

21,000 

24 

20 

1900 

35,000 

30 

23 

1500 

45,000 

36 

26 

1200 

60,000 

42 

29 

1000 

75,000 

48 

32 

800 

90,000 

54 

35 

700 

100,000 

60 

40 

650 

120,000 

66 

45 

575 

140,000 

72 

50 

500 

170,000 

84 

55 

420 

210,000 

96 

60 

350 

260,000 

120 

65 

275 

350,000 

144 

70 

225 

420,000 

168 

75 

200 

450,000 

192 

80 

180 

500,000 

216 

85 

170 

575,000 

240 

90 

160 

650,000 

264 

92 

150 

700,000 

288 

95 

140 

800,000 

300 

100 

130 

900,000 

312 

105 

120 

1,200,000 

The  following  illustration,  Fig.  17,  shows  a  Robinson 
disc  fan  operated  by  electric  motor  and  chain  drive.  It 
is  used  where  the  development  does  not  justify  the  installa- 
tion of  a  centrifugal  fan  and  is  highly  efficient  when  placed 
in  an  airway  to  boost  along  feeble  currents.  It  is  easily 
installed  and  can  be  moved  from  place  to  place  as  the 
condition  of  the  mine  may  require.  In  order  to  reverse 
the  air  current  it  is  only  necessary  to  change  the  direction 
of  rotation. 

THE  SIROCCO  FAN  (Fig.  18) — The  special  advantages 
presented  by  this  fan  are:  (1)  large  inlet  area;  (2)  uniform 
action  over  the  whole  periphery,  due  to  the  large  number 


110  MINING  AND  MINE  VENTILATION 


FIG.  17. 


FIG.  18. 


MINE  VENTILATION  111 

of  blades;  (3)  absence  of  whirlpool  motion  of  the  entering 
air  before  reaching  the  fan  blades,  thereby  avoiding  the 
expenditure  of  power  on  unnecessary  work;  (4)  the  blades 
are  so  constructed  and  arranged  that  the  power  consuming 
eddies  are  minimized. 

Instead  of  the  work  being  done  by  12  or  16  blades,  as 
in  the  majority  of  old  fans,  the  Sirocco  has  128  blades  in  the 
double-inlet  type  of  fan,  thereby  securing  uniformity  of 
action  around  the  entire  circumference. 

Fig.  19  shows  a  single-inlet  reversible  fan  and  fan  drift 
installed  at  a  drift  mouth,  and  Fig.  20  shows  a  double- 
inlet  reversible  fan  on  a  shaft  mine. 

It  frequently  happens  that  a  fan  installed  at  a  mine 
cannot  create  sufficient  pressure  to  cause  the  proper  volume 
of  air  to  circulate  through  the  remote  parts  of  the  mine. 
To  remedy  this  difficulty  a  booster  fan  (Fig.  21)  is  some- 
times installed  at  a  convenient  point  in  the  airway.  In 
all  such  installations,  however,  the  pressure  produced  by 
the  booster  must  be  above  the  pressure  of  the  air  current 
at  the  point  of  installation.  If  the  booster  is  unable  to 
produce  a  greater  pressure  than  is  already  in  the  air  cur- 
rent, then  it  will  be  unable  to  increase  the  volume. 

Below  is  given  a  table  of  approximate  capacities  of 
various  sizes  of  Sirocco  fans  against  varying  resistances. 
As  stated,  no  definite  rule  can  be  given  by  which  the  quan- 
tity of  air  a  fan  will  cause  to  flow  through  a  mine  can  be 
calculated,  unless  the  exact  mine  conditions  are  known. 
A  fan  listed  in  the  tables,  given  herewith,  as  being  capable 
of  producing  150,000  cu.ft.  of  air  per  minute  at  a  2-in. 
water  gauge  might  be  placed  at  a  mine  in  which  the  air- 
ways are  such  that  the  pressure  is  only  sufficient  to  over- 
come friction  and  cause  little  or  no  velocity. 

If  economy  and  efficient  ventilation  are  desired  it  is 
absolutely  necessary  that  the  manufacturer  know  the 


112  MINING  AND  MINE  VENTILATION 


MINE  VENTILATION 


113 


114  MINING  AND  MINE  VENTILATION 


MINE  VENTILATION 


115 


116  MINING  AND  MINE  VENTILATION 

TABLE  L 


Volume 
Cu.ft. 
Per  Min. 

Static 
Pressure 
in  w.g. 

Approx. 
H.P.  Re- 
quired. 

Size  and  Speed  of  Fan  Wheel. 

Single  Inlet. 

Double  Inlet. 

Diam.  Width. 

R.P.M. 

Diam.  Width. 

R.P.M. 

ins. 

ft.  in.  ft.  in. 

ft.   in.  ft.  in. 

40,000 

1 

8 

7   0X3    6 

124 

5   0X5  0 

172 

1 

11 

6   6X3   3 

154 

4   6X4  6 

224 

U 

16 

6  0X3   0 

205 

4  0X4  0 

310 

2 

21 

6  0X2   6 

235 

4  0X3   6 

358 

60,000 

1 

16 

8   0X4  0 

124 

5   6X5   6 

185 

if 

24 

8   0X3  0 

156 

5  6X4   6 

224 

2 

32 

7   6X2   10 

190 

5  0X4  6 

282 

3 

48 

7   0X2   6 

250 

5  0X3   8 

346 

80,000 

1 

21 

9   0X4   6 

102 

6   6X6   6 

154 

2 

42 

8   6X3   2 

170 

6  0X5  0 

235 

3 

63 

8  0X2    10 

220 

6  0X4  0 

288 

4 

84 

8   0X2   8 

250 

5   6X3   8 

366 

100,000 

2 

53 

10  0X3   6 

143 

7   0X5  0 

204 

3 

80 

9   6X3  2 

182 

6   6X4  4 

270 

4 

107 

9   0X2   10 

222 

6  0X4  4 

333 

5 

133 

9  0X2  8 

248 

6  0X3   8 

376 

125,000 

2 

66 

11   0X4  0 

130 

8   0X5  8 

176 

3 

100 

10  6X3   6 

166 

7   6X5  0 

232 

4 

133 

10  0X3  2 

200 

7   0X4  8 

285 

5 

167 

10  0X3  0 

222 

7   0X4  0 

322 

150,000 

2 

80 

12   0X4  4 

120 

8   6X6  4 

167 

3 

120 

11    6X3    10 

151 

8   0X5   4 

220 

4 

160 

11   0X3   6 

182 

7   6X5  0 

268 

5 

200 

11   0X3   4 

202 

7   6X4  8 

298 

175,000 

2 

93 

13   0X4  8 

110 

9   6X6  8 

149 

3 

140 

12   6X4  2 

138 

9   0X5  8 

193 

4 

187 

12   0X3   8 

168 

8   6X5   4 

236 

5 

234 

11    6X3   6 

195 

8   6X5   0 

263 

MINE  VENTILATION 
TABLE  L — Continued 


117 


Size  and  Speed  of  Fan  Wheel. 

Volume 
Cu.ft. 
Per  Min. 

Static 
Pressure 
in  w.g. 

Approx. 
H.P    Re- 
quired. 

Single  Inlet. 

Double  Inlet. 

Diam.   Width.  R.P.M. 

Diam.  Width. 

R.P.M. 

ins. 

ft.  in.    ft.  in. 

ft.  in.  ft.  in 

200,000 

3 

160 

13   0X4   4 

136 

9   6X6   4 

182 

4 

214 

12    6X4   2 

160 

9  0X5   8 

222 

5 

266 

12   0X3    10 

186 

9  0X5   4 

248 

6 

320 

11    6X3   8 

214 

8   6X5  0 

288 

250,000 

3 

200 

14   6X5   0 

120 

10  6X7   0 

166 

4 

266 

14  0X4  6 

144 

10  0X6   4 

200 

5 

334 

13   6X4  2 

166 

10  0X6  0 

222 

6 

400 

13   0X4  0 

188 

10  0X5   6 

247 

300,000 

3 

240 

16  0X5   6 

108 

11    6X7   8 

151 

4 

320 

15   6X5  0 

129 

11   0X7   0 

182 

5 

400 

15   0X4  8 

148 

11   0X6  8 

202 

6 

480 

14  6X4   6 

168 

10   6X6   4 

232 

350,000 

4 

374 

16   6X5   4 

122 

12   0X7   4 

168 

5 

468 

16  0X5   0 

140 

11    6X7  0 

195 

6 

560 

15   6X4    10 

157 

11   0X6  8 

224 

7 

655 

15  0X4   8 

175 

10   6X6   4 

254 

400,000 

5 

532 

17   0X5   4 

132 

12   0X7   8 

186 

6 

640 

16   6X5  2 

148 

11    6X7   4 

214 

7 

746 

16  0X5  0 

165 

11    6X7  0 

230 

8 

854 

15   6X4   10 

182 

11    6X7   0 

244 

mine   conditions   or  the   pressure   that   will  be   consumed 
in  circulating  the  quantity  of  air  desired. 

Fig.  22  shows  a  Sirocco  Ventura  Disc  Mine-fan.  The 
Ventura  Disc-Mine  Fan  is  the  latest  achievement  in  the 
development  of  this  class  of  apparatus.  It  is  especially 
adapted  to  the  ventilation  of  drift  mines  and  for  develop- 


118  MINING  AND  MINE  VENTILATION 


FIG.  22. 


MINE  VENTILATION 


119 


merit  work  on  new  operations.  It  should  be  carefully  noted, 
however,  that  speed  considerations  limit  the  application  of 
this  type  of  fan  to  mines  where  a  high-water  gauge  is  not 
required. 

JEFFREY  FAN. — Fig.  23  shows  the  extreme  sizes  and 
construction  of  the  Jeffrey  fan  wheel.  The  high  effici- 
ency developed  by  this  fan  is  primarily  due  to  the  relative 


FIG.  24. 

position  and  curvature  of  the  blades,  which  are  so  arranged 
that  the  air  is  discharged  in  a  forward  direction,  and  each 
blade  is  backed  up  by  an  auxiliary  blade  which  prevents 
eddy  currents  and  the  slippage  of  air. 

The  conical  scoops,  by  their  special  form  and  position 
prevent  the  gushing  of  air  from  the  inlet  when  working 
against  a  high  water  gauge. 

Fig.  24  shows  plan  and  side  view  of  a  double  inlet 
exhaust  reversible  fan  with  explosion  cover,  on  a  shaft 
mine. 


120 


MINING  AND  MINE  VENTILATION 


TABLE  M 

PERIPHERAL  SPEEDS  OF  FAN  REQUIRED  FOR  THEORET- 
ICAL WATER   GAUGE 


Ins.  Water  Gauge. 

Velocity,  Ft.  per 

Min. 

Ins.  Water  Gauge. 

Velocity,  Ft.  per 
Min. 

i 
4 

1390 

5 

6216 

1 

1966 

5J 

6369 

1 

2407 

&i 

6520 

1 

2780 

51 

6666 

If 

3108 

6 

6809 

if 

3405 

61 

7087 

If 

3677 

7 

7355 

2 

3931 

71 

7613 

2* 

4170 

8 

7863 

2* 

4395 

8| 

8105 

21 

4610 

9 

8340 

3 

4815 

9£ 

8568 

3i 

5012 

10 

8791 

3^ 

5201 

10i 

9008 

3! 

5383 

11 

9220 

4 

5560 

111 

9427 

4i 

5731 

12 

9630 

4£ 

5897 

12* 

9828 

4| 

6059 

13 

10023 

The  following  table  gives  a  comprehensive  idea  of  the 
results  obtained  from  various  sizes  of  Jeffrey  mine  fans. 
It  is  understood  that  the  proportions  of  the  fans  may  be 
changed  to  meet  other  conditions,  that  is,  a  fan  may  be 
built  wider  to  handle  economically  a  larger  volume  at  the 
same  gauge,  or  on  the  other  hand  the  fan  may  be  built 
narrower  to  handle  a  smaller  volume  at  the  same  gauge 
while  the  speed  of  the  fan  remains  constant. 


MINE  VENTILATION 


121 


TABLE  N 

DOUBLE    INLET 


Water  Gauge,  Ins. 

Volume. 

R.P.M. 

H.P. 

2-ft.  Fan. 

1 

A 

6,000 

260 

| 

i 

8,000 

367 

1 

f 

10,000 

448 

1.8 

i 

12,000 

520 

3 

11 

15,000 

633 

5.5 

2 

17,000 

734 

8 

4-ft.  Fan. 

i 

25,000 

183 

3 

I 

31,000 

224 

6 

i 

36,000 

259 

9 

H 

44,000 

317 

17 

2 

50,000 

366 

25 

3 

62,000 

450 

46 

6-ft.  Fan. 

i 

40,000 

122 

5 

1 

56,000 

172 

14 

H 

70,000 

211 

24 

2 

80,000 

244 

36 

3 

100,000 

294 

67 

8-ft.  Fan. 

1 

75,000 

124 

17 

U 

91,000 

152 

30 

2 

106,000 

176 

47 

3 

129,000 

215 

86 

4 

150,000 

248 

133 

10-ft.  Fan. 

1 

100,000 

100 

22 

1| 

123,000 

123 

42 

2 

141,000 

141 

62 

3 

173,000 

173 

115 

4 

200,000 

200 

178 

12-ft.  Fan. 

1 

125,000 

84 

28 

2 

177,000 

119 

79 

3 

218,000 

146 

145 

4 

250,000 

168 

222 

5 

280,000 

188 

311 

122 


MINING  AND  MINE  VENTILATION 


TABLE  N — Continued 

DOUBLE    INLET 


Water  Gauge,  Ins. 

Volume. 

R.P.M. 

H.P. 

14-ft.  Fan. 

1 

150,000 

70 

33 

2 

214,000 

100 

95 

3 

261,000 

122 

174 

4 

300,000 

140 

267 

5 

338,000 

158 

376 

16-ft.  Fan. 

1 

175,000 

63 

39 

2 

245,000 

88 

109 

3 

200,000 

108 

200 

4 

350,000 

126 

311 

5 

386,000 

139 

430 

18-ft.  Fan. 

1 

200,000 

56 

45 

2 

283,000 

79 

125 

3 

344,000 

96 

230 

4 

400,000 

112 

355 

5 

443,000 

124 

492 

6 

485,000 

136 

647 

20-ft.  Fan. 

1 

225,000 

50 

50 

2 

315,000 

70 

140 

3 

380,000 

85 

250 

4 

450,000 

100 

400 

5 

495,000 

110 

550 

6 

540,000 

120 

720 

The  most  important  factors  to  be  considered  in  the 
construction  of  mine  airways  are  the  main  intake  and 
return  shafts.  All  the  air  entering  the  mine  must  pass 
through  those  openings,  and  if  their  sectional  areas  are 
small,  the  velocity  will  necessarily  be  high  and  a  large 
part  of  the  total  pressure  generated  by  the  ventilating 
equipment  will  be  consumed  in  the  shafts.  In  the  mine 


MINE  VENTILATION 


123 


workings  it  is  different.  In  case  the  consumption  of  pres- 
sure is  high,  the  mine  can  be  divided  into  districts  and 
ventilated  by  separate  and  independent  air  currents;  by 
this  means  the  velocity  is  reduced  in  that  part  of  the  mine 
in  which  the  air  current  is  divided.  By  reason  of  this 
reduction  in  velocity  the  pressure  consumed  is  also  reduced. 
Part  of  the  pressure  thus  saved  is  converted  into  velocity 


A  Jeffrey  Double  Inlet  Exhaust  Reversible  Fan. 

pressure  and  the  remainder  is  used  up  in  overcoming  the 
friction,  caused  by  reason  of  the  increased  volume  obtained 
by  splitting. 

In  the  case  of  shafts  the  pressure  consumed  remains 
constant  while  the  velocity  remains  constant,  and  nothing 
can  be  done  with  the  ventilating  arrangement  in  the  mines 
that  will  reduce  the  pressure  consumed  in  the  shafts,  and 
at  the  same  time  maintain  the  same  quantity  of  air. 

It  is  therefore  recommended  that  the  main  airways 
be  of  sufficient  area  to  allow  the  passage  of  the  desired 
volume  of  air  at  a  velocity  not  exceeding  1000  ft.  per  minute. 


124  MINING  AND  MINE  VENTILATION 

Any  reduction  in  velocity  brought  about  by  an  increase 
in  the  area  of  the  airways  will  reduce  the  pressure  and 
horse-power  necessary  to  maintain  the  same  quantity. 

The  following  examples  will  better  illustrate  the  extrav- 
agant use  of  power  by  reason  of  high  velocities: 

EXAMPLE  1.  —  The  return  air  shaft  of  a  mine  is  10  ft. 
by  10  ft.  in  section  and  1000  ft.  deep;  the  quantity  of 
air  desired  is  400,000  cu.ft.  per  minute.  What  pressure 
and  horse-power  will  be  required  to  do  the  work? 

ksv2    .00000001  X  40,000  X40002 
P  =  ~^~''  100  -  =  64  Ibs.  per  sq.ft. 

„         400,000X64 

33,000  -  =776     H'R 

In  the  following  example  we  will  change  the  sectional 
area  of  the  shaft,  using  the  same  quantity  and  depth: 

EXAMPLE  2.  —  The  return  air  shaft  of  a  mine  is  12  ft. 
by  15  ft.  in  section,  and  1000  ft.  deep;  the  quantity  of 
air  desired  is  400,000  cu.ft.  per  minute.  What  pressure 
and  horse-power  will  be  required  to  do  the  work? 

ksv2     .00000001  X  54,000  X  22222  ., 

P  =  —  =  ~  ~~  -  =  14.8  Ibs.  per  sq.ft. 


400,000X14.8 

33,000  H'r''       , 

or  a  saving  under  the  second  condition,  of  776  —  179.3  = 
596.7  H.P. 

At  a  cost  of  $62.08  per  horse-power  per  year  a  saving 
of  596.7  H.P.  will  amount  to  $37,043. 

The  consumption  of  power  in  the  ventilation  of  mines 
is  an  important  item  in  the  burden  account,  full  of  possi- 
bilities for  saving.  At  a  certain  mine  in  *d  .  .3  -i 


MINE  VENTILATION 


125 


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<M  10  10  T*H  o  co  eo 


indui  -J- 


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9d  ISOQ 


M-"      v^i      <^?      ^p      L^~ 

38888 


GO    I"—    O    CO    t—    T}<    00 

Tt<   Tf    CO   CO   I>-   CO  t>- 


<N    C< 


O 

9 


^  CD  CO  CO  tO  00  CO 

00  t^*  ^^  OO  CO  *O    CO    ^D 

(H  C*l  CO  *^  ^^  C^  00    CO    *-O 

£ 


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Tt^     1C  CO     t^.     Tfl 

^H    10    O^   C^    O5   CO    O^    00 


CO   !>•    Is*    CO    T—I    !>• 

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|>    CO    i— l    i— I 

CO    d     rH     IO    IO 


s00 


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T-H      1-1      T-H      CO      Tj< 


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cxT  TjT  co"  cT  rj^ 

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126  MINING  AND  MINE  VENTILATION 

324  H.P.  is  consumed  by  the  ventilating  equipment,  while 
only  98  H.P.  is  effective  in  the  ventilation  of  the  mine; 
this  involves  a  direct  loss  of  226  H.P.  input  or  226  X  $62.08  = 
$14,030  per  year.  (For  cost  per  H.P.,  refer  to  Table  0.) 

Table  O  shows  a  comparison  of  several  fans  in  actual 
operation.  The  facts  contained  therein  were  obtained  by 
careful  trial.  In  determining  the  cost  per  horse-power 
input,  only  the  fuel,  water  and  operating  charges  are 
used;  no  allowance  has  been  made  for  maintenance  or 
interest  on  investment. 

88.  Installation  of  Fan. — When  about  to  install  a 
mine- ventilating  fan  all  the  factors  which  go  to  make  up 
the  resistance  encountered  by  the  moving  air  should  be 
considered;  and  in  case  the  mine  airways  have  not  reached 
the  boundary  lines  a  complete  projection  should  be  made 
of  the  proposed  workings  of  the  entire  mine.  The  pressure 
necessary  to  circulate  the  required  volume  of  air  should 
then  be  calculated  for  the  conditions  which  will  exist  when 
the  workings  have  reached  their  limit,  at  which  point  the 
maximum  resistance  will  be  encountered  by  the  air. 

If  it  be  decided  that  150,000  cu.ft.  of  air  per  minute 
will  be  required  to  ventilate  a  certain  mine  it  will  be  neces- 
sary, first,  to  calculate  the  pressure  that  will  be  consumed 
in  producing  this  quantity  in  order  that  the  dimensions, 
speed,  water  gauge  and  horse-power  of  the  fan  can  be 
determined. 

The  steps  to  be  taken  when  determining  the  pressure 
required  to  pass  this  volume  of  air  are  as  follows: 

First,  calculate  the  pressure  required  to  pass  the  air 
through  the  main  intake  to  the  point  where  the  first  split 
branches  off. 

Second,  calculate  the  pressure  required  to  overcome 
the  resistance  of  the  main  return  airway  from  the  point 
where  the  last  split  of  air  is  returned  into  it,  to  the  fan. 


MINE  VENTILATION  127 

Third,  calculate  the  pressure  necessary  to  pass  the 
required  volume  of  air  through  the  hardest  split.  In 
connection  with  this  the  resistance  of  the  main  intake 
airway,  from  the  point  where  the  first  split  is  taken  off 
to  the  beginning  of  the  split  under  consideration  must  be 
included. 

The  pressure  consumed  in  forcing  air  through  the 
hardest  split  will  be  equal  to  the  pressure  consumed  in 
all  other  splits,  because  the  resistance  offered  by  the  easier 
splits  must  be  raised  by  means  of  regulators  to  that  of  the 
split  consuming  the  most  pressure.  Therefore  the  sum 
of  the  three  pressures,  found  as  described,  will  be  the  pres- 
sure required  to  overcome  the  total  mine  resistance. 

In  addition  to  the  pressure  already  found  a  reasonable 
allowance  might  be  made  for  contraction  of  area  due  to 
brattices  at  the  working  faces. 

Now  we  will  suppose  it  is  discovered  by  calculation 
that  the  pressure  necessary  to  overcome  the  friction  of 
the  mine  under  consideration,  and  create  sufficient  velocity 
to  circulate  the  required  volume  of  air,  namely,  150,000 
cu.ft.  per  minute,  is  equal  to  a  3-in.  water  gauge. 

It  now  remains  to  proportion  a  fan  for  a  3-in.  actual 
water  gauge  and  150,000  cu.ft.  of  air  per  minute.  In  order 
to  do  this  the  peripheral  speed  necessary  to  create  this 
water  gauge  must  be  found,  but  as  the  actual  water  gauge 
at  a  fan  is  seldom  more  than  80  per  cent  of  the  theoretical 
water  gauge,  it  will  be  necessary  to  raise  the  3-in.  actual 
water  gauge  to  the  theoretical  water  gauge,  which  in  this 
case  will  be  3.75  ins.  Then, 


v= 


.078 


peripheral  or  rim  speed  at  which  the  fan  must  run  per  minute 
to  create  an  actual  water  gauge  of  3  ins. 


128  MINING  AND  MINE  VENTILATION 

It  is  now  necessary  to  decide  on  diameter  of  fan  desired. 
If  a  small  diameter  fan  be  employed  and  it  is  to  be  direct- 
connected  to  an  engine,  no  doubt  the  operator  would  seri- 
ously object  to  the  speed  at  which  his  engine  must  run 
to  produce  the  required  water  gauge;  then  it  will  be  neces- 
sary to  go  into  a  larger  diameter  of  fan  to  get  the  gauge 
at  a  rotated  speed  which  would  be  acceptable.  In  case 
of  a  belt-driven  equipment  it  is  an  easy  matter  to  make 
the  required  reductions  between  engine,  motor  or  fan 
pulleys. 

However,  we  will  select  a  10-ft.  diameter  fan.  The 
number  of  revolutions  at  which  this  fan  must  run  to  pro- 
duce the  required  water  gauge  is  found  as  follows: 

peripheral  speed  required  to  produce  the  water  gauge 

circumference  of  fan 
or 

5380  5380 


3.1416X10    31.4160 


=  171R.P.M. 


We  must  now  find  the  width  for  a  10-ft.  fan  capable 
of  discharging  the  required  volume  of  air  while  running 
at  171  R.P.M.  and  at  the  same  time  show  a  reasonable 
volume  ratio.  Some  manufacturers  figure  a  volume  ratio 
of  about  250  per  cent.  The  meaning  of  this  is,  that  if  the 
volume  of  a  fan  is  100  cu.ft.,  it  must  deliver  250  cu.ft.  of 
air  for  each  revolution  of  the  wheel  in  order  to  have  a 
volume  ratio  of  250  per  cent. 

If,  however,  we  reduce  this  volume  ratio  to  200  per  cent 
to  allow  for  any  added  friction  that  might  interfere  with 
the  movement  of  the  air  from  time  to  time,  the  width  of 
the  fan  can  then  be  found  as  follows: 


.7854XD2XR.P.M. 


W, 


MINE  VENTILATION  129 

or  width  for  fan  having  100  per  cent  volumetric  capacity. 

W 

—  =  W  f or  fan  200  per  cent  volumetric  capacity. 

2i 

Then, 

150,000 
.7854X100X171 

ft.  width  for  fan  of  100%  volume  ratio, 
or 


or  say  6  feet  wide  required  width  for  fan  of  200%  volume 
ratio. 

To  find   the   actual   horse-power   in  the    air    (output) 
delivered  by  the  fan: 

150,000X3X5.2 
33,000 

To  find  the  horse-power   (input)   of   motor   or   engine 
required  to  drive  the  fan: 

q  X  w.g.  _  150,000  X  3" 
4500    :          4500 

To   find   the   mechanical   efficiency   of   the   ventilating 
equipment  : 

71  H.P. 

ir>r>  TT  ^>  =<1  per  cent  mechanical  efficiency. 

1UU  ri.r. 

To  find  the  manometric  efficiency  of  the  fan: 


0  _,„      — 
3.75    w.g. 


=  80  per  cent  manometric  efficiency. 


130  MINING  AND  MINE  VENTILATION 

SUMMARY 

Diameter  of  fan 10  feet 

Width  of  fan 6  feet 

Revolutions  of  fan  per  minute 171 

Actual  water  gauge 3  inches 

Theoretical  water  gauge 3.75  ins. 

Quantity  of  air  delivered  per  minute .  .    150,000  cu.ft. 

Volumetric  capacity 200  per  cent 

Horse-power  output 71 

Horse-power  input 100 

Mechanical  efficiency 71  per  cent 

Manometric  efficiency 80  per  cent 

If  it  now  be  required  to  proportion  a  fan  for  a  5-in. 
actual  water  gauge  instead  of  a  3-in.,  and  150,000  cu.ft. 
of  air,  using  the  same  diameter  of  fan,  namely,  10  ft.,  it 
is  evident  that  the  fan  will  have  to  run  faster  to  generate 
the  larger  gauge;  then  if  we  figure  on  the  same  volume 
ratio  it  will  be  necessary  to  build  the  fan  narrower. 

89.  Motive  Column. — The  motive  column  is  a  column 
of  air  in  the  downcast  shaft  the  weight  of  which  is  the 
difference  between  the  weight  of  the  downcast  and  upcast 
columns;  therefore  if  the  length  of  the  motive  column 
be  subtracted  from  the  downcast  column,  the  remaining 
portion  of  the  downcast  column  will  be  equal  in  weight 
to  the  upcast  column. 

EXAMPLE. — At  a  certain  mine  there  are  two  shafts 
500  ft.  deep.  The  temperature  in  the  downcast  shaft 
is  50°  F.,  and  the  temperature  of  the  upcast  air  is  150°  F.; 
what  is  the  motive  column? 


Solution.— M  = 


MINE  VENTILATION  131 

t  =  temperature  of  air  in  the  upcast; 

t'  =  temperature  of  air  in  the  downcast; 
D  =  depth  of  shaft  in  feet; 
M  =  motive  column. 

(150-50)  .x 500  =  82.1  feet  motive  column. 


(459  +  150) 

If  in  the  above  example  the  barometer  pressure  is 
equal  to  30  ins.  and  it  is  desired  to  find  the  pressure  per 
square  foot,  the  weight  of  a  cubic  foot  of  air  in  the  down- 
cast shaft  must  first  be  found.  Thus, 

1.3253  XB 

~~  (459+0  ' 

in  which  B  =  the  barometric  pressure  in  inches; 

t  =  temperature  of  the  air  in  the  shaft; 
W  =  weight  per  cubic  foot. 

Applying  formula: 

w     1.3253X30     n7ftl 
W  =  (459+50)  ='07811b- 

Now  if  the  height  of  the  motive  column  is  82.1  feet  and 
the  weight  of  a  cubic  foot  of  air  in  the  downcast  shaft 
is  .0781  lb.,  the  pressure  per  square  foot  is: 

82. 1 X  .0781  =  6.41  Ibs.    Ans. 

EXAMPLE. — The  temperature  of  the  air  in  a  downcast 
shaft  is  60°  F.  and  in  the  upcast  shaft  170°  F.;  the  shafts 
are  900  ft.  deep.  If  the  barometer  reading  is  30  ins.,  what 
is  the  pressure  per  square  foot? 

EXAMPLE. — There  are  two  shafts  600  ft.   deep.     The 


132  MINING  AND  MINE  VENTILATION 

temperature  in  the  upcast  shaft  is  180°  F.,  and  the  tem- 
perature of  the  downcast  air  is  40°  F.;  what  is  the  motive 
column? 

EXAMPLE. — What  is  the  weight  of  a  cubic  foot  of  air 
at  a  temperature  of  60°  F.  when  the  barometer  reading  is 
30  ins.? 

90.  Splitting  the  Air  Current. — By  splitting  air  means 
the  dividing  of  the  main  intake  current  into  two  or  more 
separate  currents,  the  purpose  of  which  is  to  ventilate 
the  different  independent  districts  of  a  mine  with  air  that 
is  not  vitiated  by  the  smoke  or  gases  from  another  dis- 
trict. 

The  advantage  derived  from  splitting  the  air  is  as 
follows : 

(1)  A  larger  volume  of  air  with  the  same  power.     The 
extent  of  the  increase  in  volume  will  depend  on  how  nearly 
equal  the  splits  are. 

(2)  Purer  air  circulated  through  the  working  faces. 

(3)  An  explosion  or  fire  in  one  district  is  not  likely 
to  affect  the  other  districts. 

(4)  A  fall  of  roof  affects  only  the  section  in  which  it 
occurs. 

(5)  The  velocity  of  the  air  is  kept  within  a  reasonable 
limit  in  a  greater  portion  of  the  mine. 

Fig.  25  shows  an  air  bridge  or  overcast.  Such  struc- 
tures are  necessary  when  it  is  desired  to  pass  one  current 
of  air  over  or  under  another  current.  The  sides  and  floors 
of  air  bridges  are  usually  constructed  of  concrete.  By 
the  use  of  overcasts  the  main  air  current  can  be  divided 
and  conducted  across  one  another  for  the  purpose  of  ven- 
tilating the  different  districts  of  a  mine.  Sometimes  an 
undercast  bridge  is  employed  for  the  same  purpose  as 
an  overcast,  but  there  is  the  liability  of  water  flooding  them 
and  blocking  the  air. 


MINE  VENTILATION 


133 


The  following  examples  will  show  the  effect  of  splitting 
a  continuous  air  current  into  several  splits: 

EXAMPLE.— An  airway  is  6  ft.  by  10  ft.  and  16,000  ft. 
long.  What  power  will  be  required  to  circulate  24,000 
cu.ft.  of  air  through  this  airway? 

Solution. 
_  ks<?  _  .0000000217  X  32  X  16,000  X  24,QOQ3  _ 


603 


711,066  ft.-lbs.     Ans. 


ET  I.     I.    I.    I  .    1.     ' 


FIG.  25. 

EXAMPLE  2. — Suppose  the  air  in  the  above  mine  be 
so  circulated  and  divided  that  we  have  four  splits  each 
4000  ft.  long,  the  quantity  of  air  being  24,000  cu.ft.  and 
each  airway  is  6  ft.  by  10  ft.  in  section;  what  power  will 
be  required  to  circulate  the  air? 

Solution. 
_  ks<f  _  .0000000217  X  128,000  X  60003  X4 


603 


11,110  ft.-lbs.     Ans. 


134 


MINING  AND  MINE  VENTILATION 


The  above  examples  show  a  saving  of  699,956  foot- 
pounds per  minute  by  reason  of  splitting  the  continuous 
current,  as  stated  in  the  problem,  into  four  equal  splits; 
however,  it  is  quite  impossible  in  practice  to  divide  a  mine 
into  equal  splits  or  sections  on  account  of  the  fact  that 
a  section  of  a  mine  may  be  in  operation  for  a  year  or  more 
before  another  section  is  started,  consequently  the  splits 
will  be  unequal  and  the  advantages  obtained  in  power 


FIG.  26. 

saved  by  reason  of  splitting  will  not  be  as  great  as  in  the 
case  of  equal  splitting.  The  reason  for  this  is  that  in 
nearly  all  cases  of  unequal  splitting  regulators  are  required. 

91.  Regulators. — Any  partition  constructed  of  boards, 
canvas,  or  any  other  material  placed  across  an  airway 
is  termed  a  regulator.  The  usual  method  of  construction 
is,  however,  the  erecting  of  a  board  stopping  across  an 
airway  (Fig.  26),  in  which  stopping  a  shutter  or  door  is 
so  arranged  that  it  can  be  moved  in  grooves  and  thereby 
allow  the  passage  of  the  quantity  of  air  desired. 

Regulators  as  stated  are  principally  used  in  cases  of 


MINE  VENTILATION  135 

unequal  splitting.  Thus,  if  in  a  mine  there  are  two  splits, 
in  one  of  which  there  are  700,000  sq.ft.  of  rubbing  surface 
and  in  the  other  400,000  sq.ft.,  it  is  evident  that  more 
air  will  pass  through  the  split  having  the  least  rubbing 
surface;  therefore,  in  order  that  equal  quantities  pass 
through  each,  if  so  desired,  a  regulator  must  be  placed 
in  the  airway  having  the  400,000  sq.ft.  of  rubbing  surface 
in  order  to  cause  the  desired  division. 

A  regulator  placed  in  an  airway  is  equivalent  to  length- 
ening the  airway. 

The  introduction  of  a  regulator  in  a  mine  increases 
the  mine  resistance  and  reduces  the  total  quantity  of  air; 
therefore  regulators  should  not  be  used  where  it  is  possible 
to  obtain  the  desired  division  of  the  air  without  them. 

EXAMPLE. — Suppose  we  have  two  airways,  A  and  B. 
A  has  an  area  of  30  sq.ft.  and  a  rubbing  surface  of  66,000 
sq.ft.,  and  B  has  an  area  of  36  sq.ft.  and  a  rubbing  surface 
of  96,000  sq.ft.  What  quantity  of  air  will  pass  in  each 
split  if  the  total  quantity  entering  the  mine  is  50,000  cu.ft. 
per  minute? 

Solution. 

A=q=\r:Xa= 


66,000' 

.6969 


A  =jf!||x  50,000  =  23,926g.     Ans. 


fiQfiQ 

X  50,000  =  26,074g.    Ans. 


136  MINING  AND  MINE  VENTILATION 

EXAMPLE. — 50,000  cu.ft.  of  air  are  entering  a  mine. 
If  the  current  is  divided  into  three  splits  of  the  following 
dimensions: 

1st,   6  ft.  by  6  ft.  and  4000  ft.  long; 
2d,  5  ft.  by  6  ft.  and  3000  ft.  long; 
3d,  5  ft.  by  5  ft.  and  4000  ft.  long, 

what  quantity  will  pass  through  each  of  the  splits? 

Ans.  1st,    19,597  cu.ft.  per  min. 
2d,  17,980  cu.ft.  per  min. 
3d,  12,423  cu.ft.  per  min. 

EXAMPLE. — If  20,000  cu.ft.  of  air  passes  per  minute 
through  an  airway  and  it  is  desired  to  reduce  the  quantity 
to  8000  cu.ft.  by  means  of  a  regulator,  what  must  be  the 
area  of  the  opening  if  the  difference  of  pressure  on  the 
two  sides  of  the  regulator  is  equivalent  to  J-in.  water  gauge? 

.0004g 

volution. — A  =  — -1= , 

in  which  A  =area  of  opening  in  square  feet; 
q  —  quantity  of  air  desired  to  pass; 
W  =  difference  of  pressure  in  inches  of  water  on 
the  two  sides  of  the  regulator. 

Applying  formula: 

.0004X?     .0004X8000  ,, 

A= 7=-i=—     —7= =  6.4  sq.ft.     Ans. 

VW  Vj 

92.  Resistance. — The  several  causes  of  resistance  met 
with  by  the  air  while  moving  through  a  mine  are  as  follows : 


MINE  VENTILATION  137 

First.  The  resistance  offered  by  the  sides,  top  and 
bottom  of  the  airway. 

Second.  The  resistance  due  to  turns  in  the  airway. 

Third.  The  resistance  due  to  the  sudden  expansion 
and  contraction  of  the  airway. 

Fourth.  The  resistance  due  to  moving  trips  and  cars 
standing  in  the  airway. 

Fifth.  The  resistance  due  to  regulators. 

First.  The  resistance  offered  to  the  air  by  reason  of  its 
rubbing  on  the  sides,  top  and  bottom  of  the  airway  is  the 
most  important  source  and  is  the  heaviest  consumer  of 
pressure.  In  rough-timbered  airways  the  resistance  will 
be  higher  than  in  smooth  airways. 

Second.  The  resistance  due  to  turns  or  bends  in  the  air- 
ways of  a  mine  can  be  disregarded  where  the  velocity 
of  the  air  is  low,  but  where  the  velocity  is  high  and  the 
air  is  forced  around  a  right-angle  turn,  the  amount  of 
pressure  consumed  by  reason  of  this  source  of  resistance 
is  serious.  When  bends  are  necessary  they  should  be  as 
large  as  the  circumstances  will  permit  so  as  to  change  the 
direction  of  the  air  gradually.  Sudden  changes  in  direc- 
tion will  destroy  the  velocity  very  rapidly  and  consequently 
reduce  the  volume. 

Third.  The  resistance  due  to  sudden  or  abrupt  expan- 
sions and  contractions  of  an  airway,  as  in  the  case  of  turns, 
can  be  disregarded  where  the  velocity  of  the  air  is  low, 
but  where  the  velocity  is  high  the  efficiency  of  the 
ventilating  equipment  is  affected.  According  to  certain 
laws  governing  the  acceleration  and  retardation  of  air 
flowing  through  the  airways  of  a  mine,  it  is  clear  that 
if  the  movement  of  the  air  can  be  accomplished  without 
abrupt  change  in  the  velocity  or  in  the  area  of  the 
airway,  static  pressure  can  be  converted  into  velocity 
pressure.  Contraction  of  area  is  sometimes  necessary 


138  MINING  AND  MINE  VENTILATION 

where  air-bridges  and  door-frames  are  erected,  but  if  the 
contraction  is  effected  gradually  when  approaching  the 
point  of  contracted  area  and  gradually  expanding  after 
passing  it  the  loss  in  volume  will  not  be  as  great  as  where 
the  contraction  and  expansion  are  abrupt. 

The  loss  due  to  the  sudden  expansion  of  an  airway 
for  a  short  distance  will  be  the  same  as  that  due  to  the 
sudden  contraction,  as  the  velocity-head  in  the  moving 
air  would  be  partly  lost  by  the  abrupt  slowing  down  of  the 
air,  and  additional  pressure  would  have  to  be  provided 
to  re-establish  the  former  velocity.  The  loss  in  volume 
by  reason  of  this  cause  will  increase  and  decrease  as  the 
squares  of  the  velocities  increase  and  decrease. 

Fourth.  The  resistance  due  to  mine  cars  moving  or 
standing  in  airways  presents  a  source  of  resistance  which 
cannot  be  removed,  but  the  interference  offered  to  the 
movement  of  the  air  can  be  reduced  to  a  minimum  if  all 
junction  points  and  other  places  where  cars  are  allowed 
to  stand  in  main  airways  be  made  of  sufficient  area  to  per- 
mit the  free  movement  of  the  air. 

Fifth.  The  resistance  due  to  regulators  can  be  removed 
only  by  equal  splitting.  In  cases  of  unequal  splitting 
it  will  be  necessary  to  place  regulators  in  the  easier  splits 
in  order  to  restrict  the  quantity  of  air  that  will  flow  through 
them.  The  regulator  is  equivalent  to  lengthening  the  air- 
way. 

If  in  a  mine  composed  of  several  unequal  splits  regula- 
tors are  omitted,  a  natural  division  of  the  air  will  take 
place;  the  airway  offering  the  least  resistance  will  receive 
the  most  air. 

QUESTIONS 

1.  State  the  different  means  by  which  ventilation  is 
produced  and  describe  each. 


MINE  VENTILATION  139 

2.  What  is  the  motive  column  and  how  is  it  produced? 

3.  If  the  temperature  of  the  air  in  the  upcast  shaft 
is  80°  F.  and  the  temperature  in  the  downcast  is  40°  F., 
what  is  the  motive  column  if  the  depth  of  each  shaft  is 
600  ft.? 

4.  What  is  the  weight  of  a  cubic  foot  of  air  at  a  temper- 
ature of  30°  F.,  the  barometer  being  30  ins.? 

5.  What  do  you  mean  by  splitting  the  air? 

6.  What  are  the  advantages  of  splitting  the  air  current 
in  a  mine? 

7.  What  is  a  regulator  and  to  what  is  it  equivalent? 

8.  Explain  equal  and  unequal  splitting? 

9.  Describe  a  mine  in  which  it  will  be  necessary  to 
construct  a  regulator. 

10.  Does  a  regulator  increase  the  mine  resistance? 

11.  If  you  had  a  mine  in  which  there  were  three  equal 
splits,  and  the  same  quantity  of  air  is  desired  for  each, 
would  regulators  be  necessary  to  produce  an  equal  division? 

12.  If  in  the  mine  (in  Question  11)  the  splits  are  unequal, 
how  many  regulators  at  most  will  be  required? 

Ans.    Two,  one  split  should  always  be  free. 

13.  In  a  mine  there  are  two  splits,  as  follows: 

A  5  ft.  by  7  ft.  and  a  rubbing  surface  of  10,000  sq.ft. ; 
B  8  ft.  by  8  ft.  and  a  rubbing  surface  of  20,000  sq.ft. 

If  100,000  cu.ft  of  air  enters  the  mine  per  minute,  how  will 
it  divide  in  the  above  splits? 

14.  In  a  mine  there  are  two  splits,  A  and  B]  a  regu- 
lator is  placed  in  A ;  it  later  develops  that  more  air  is  required 
in  split  B.     Can  the  quantity  in  B  be  increased  by  adjust- 
ing the  regulator?     If  so,  how? 

15.  10,000  cu.ft.  of  air  is  entering  an  airway  per  minute 
and  it  is  desired  to  reduce  this  quantity  to  5000  cu.ft.  by 


140  MINING  AND  MINE  VENTILATION 

means  of  a  regulator.  What  must  be  the  area  of  the  regu- 
lator opening  if  the  difference  of  pressure  on  both  sides 
of  the  regulator  is  J-in.  water  gauge? 

16.  The  upcast  shaft  is  300  ft.  deep  and  the  temper- 
ature of  the  air  in  it  is  120°  F.;  the  temperature  of  the 
downcast  air  is  45°  F.     What  is  the  height  of  the  motive 
column?  Ans.     38.86  ft. 

17.  The  air  passing  through  a  mine  is  equal  to  100,000 
cu.ft.  per  minute  and  is  divided  into  two  splits  having  equal 
cross-sections;     the   resistance   of   the   splits   are   to   each 
other  as  5  is  to  1;  what  quantity  of  air  will  pass  through 
each? 

Ans.     69,099  cu.ft.  per  min.  in  short  airway. 
30,901  cu.ft.  per  min.  in  long  airway. 

18.  What  is  the  weight  of  100  cu.ft.  of  air  when  the 
barometer  reading  is  29.3  ins.  and  the  temperature  is  32°  F.? 

Ans.     7.9  Ib. 

19.  What  conditions  are  necessary  in  order  to  produce 
natural  ventilation? 


CHAPTER  XIII 
FORMULAS 

93.  Formulas  and  Their  Application. — A  formula  is 
a  group  of  symbols  or  letters  designed  to  express  clearly 
the  operation  of  a  rule.  A  formula  may  be  expressed 
in  words,  but  it  is  more  convenient  when  symbols  are  used, 
which  show  at  a  glance  the  necessary  operations  required 
for  the  solving  of  problems. 

The  following  formulas  will  be  found  convenient  to 
the  student  when  solving  many  problems  pertaining  to 
mine  ventilation.  The  letters  used  are  usually  the  first 
letters  of  the  words  they  represent.  The  letters  and  their 
meanings  are  given  below: 

a  =  sectional  area  of  airway  in  square  feet; 
H  =  horse  power; 

f. 0000000217 
k  =  coefficient  of  friction]  .00000001 

i. 00000002 

The  coefficient  of  friction  is  the  amount  of  pressure 
in  pounds  required  to  overcome  the  resistance  offered  by 
one  square  foot  of  rubbing  surface  when  the  air  is  moving 
at  a  velocity  of  one  foot  per  minute. 

1  =  length  of  airway  in  feet; 

o  =  perimeter  of  airway  in  feet,  or  the  distance  around 
the  airway; 

141 


142  MINING  AND  MINE  VENTILATION 

p  =  pressure  in  pounds  per  square  foot; 
P  =  total  ventilating  pressure; 
q  =  quantity  of  air  in  cubic  feet  per  minute; 
s  =  rubbing  surface  in  square  feet; 
u  =  units  of  power  in  foot-pounds  per  minute; 
v  =  velocity  in  feet  per  minute; 
w.g.  =  water  gauge  in  inches  of  water. 

NOTE.  —  The  coefficient  of  friction  may  vary  in  ratio 
of  from  1  to  7  in  different  mines,  and  is  a  very  uncertain 
quantity.  The  coefficients  given  above  are  those  most 
commonly  used  for  mine  calculation. 


(!)«=*. 


FORMULAS  FOR  FINDING  THE  AREA 


/o\  ,  U 

(3)  «  =  —  -  (4)  a--. 

^000  -.      (6)fl 

pv 


FORMULAS  FOR  FINDING  THE  HORSE-POWER 

Pv 


/ON  TJ-  Pav 

~* 


33,000'  33,000' 

(11)  H  =  ^^.  (12)  H        U 


33,000* 
ksi? 


FORMULAS  143 

FORMULAS  FOR  FINDING  THE  COEFFICIENT  OF  FRICTION 
(14)  *  =  g.  (15)  *=£ 

ot/  ut/ 


FORMULA  FOR  FINDING  THE  LENGTH  OF  THE  AIRWAY 
(19)1-1. 

FORMULA  FOR  FINDING  THE  PERIMETER  OF  THE  AIRWAY 

(20)  o  =    . 


FORMULAS  FOR  FINDING  THE  TOTAL  PRESSURE  IN  POUNDS 
(21)  P  =  pa.  (22)  P  =  ksv2. 


(23)  P  =  (24)  p== 

(25)  P= 

r 

FORMULAS  FOR  FINDING  THE  PRESSURE  IN  POUNDS  PER 
SQUARE  FOOT 


(26)  p-.  (27)  p  =    . 


144  MINING  AND  MINE  VENTILATION 

(28)  p  =  w.g.X52.  (29)  p  =  #33>OOQ. 

av 

rroo  f\f\f\ 

(30)  p 


(32)  p=.  (33)  p  =        . 


(34) 


FORMULAS  FOR  FINDING  THE  CUBIC  FEET  OF  AIR 
PER  MINUTE 


(35)  q  =  av.  (36) 

^ 

(37)        #33,000  w 

P  P 

(39)  3  = 


FORMULAS  FOR  FINDING  THE  RUBBING  SURFACE  IN 
SQUARE  FEET 

(40)  s  =  ol.  (41)  s  =      . 


(«)  -. 


,..,        H33,000  u 

(44)  S  =  -'  (45)  S  =      ' 


FORMULAS  145 

FORMULAS  FOR  FINDING  THE  UNITS  OF  POWER  PER  MINUTE 

(46)  ^  =  #33,000.  (47)  u  =  pav. 

(48)  u  =  Pv.  (49)  u  =  pq. 

(50)  u  =  ksv*. 

FORMULAS  FOR  FINDING  THE  VELOCITY  IN  FEET  PER  MINUTE 


(5D  »  =  *.  (52)  ,-Jj£ 


/ro\  I  •*•  /r  A\  /lOO, 000 

(53)  v  =  \Tn-  (54)  v  = 


pa 


,KK.         #33,000  /K_N 

(55)  w  =  — ^ — -.  (56)  w 


(57)  .  =  |.  (58)  t;  =  </£. 


,.Q,          3  #33,000  ._         8 hi 

(59)  »=\/ — r .  (60)  ^  =  -\/T-. 

\       ks  \ks 

FORMULAS  FOR  FINDING  THE  WATER  GAUGE 

(61)  «M/.  =  ^. 

(62)  Theoretical  water  gauge=  ' 

oZ.ioXo.^ 

(63)  Electric  H.P.  =  ^^. 

746 


146  MINING  AND  MINE  VENTILATION 

94.  Transposition  of  Formulas. — It  is  quite  difficult 
to  memorize  all  the  formulas  pertaining  to  mine  ventila- 
tion. However,  by  memorizing  a  few  of  the  larger  group 
formulas  nearly  all  the  others  can  be  written  by  means 
of  transposing. 

ksv2 

We    have    the    formula    p  = from   which   it  is  de- 

a 

sired    to    write    the    formulas  for  k,  s,  v,  and  a.     Thus 

77  f7 

A;  =  ^,  in  which  k  is  placed  before  the  equality  sign,  p 

sv 

transferred  to  the  position  above  the  line  which  was  occu- 
pied   by    k.     All    other    quantities    occupying    a    position 
above  the  line  with  k  are  placed  below  the  line  and  the 
quantity  a  below  the  line  is  placed  above  the  line  with  p. 
Figures   are   sometimes   used   to   aid   the   beginner   in 

4X8 
grasping   the   principles   of   transposing.     Thus   16=—^— 

*    , 

*    ,  A          16X2     .      Q     16X2 
using  the  same  quantities  to  find  4;  4  =  — ^ — ,  also  8  =  — j— 

4X8 
and  2  =  -—^-.     With  a  little  practice  the  transposition  of 

formulas  can  be  readily  mastered  and  will  eliminate  the 
necessity  of  memorizing  the  great  number  used  in  ref- 
erences to  ventilation. 

The  formulas  by  which  the  following  problems  can 
be  worked  are  indicated  by  number  after  each  question. 
The  coefficient  used  in  obtaining  the  answer  given  for  the 
problems  is  .00000002. 

QUESTIONS 

1.  The  quantity  of  air  passing  through  an  airway  per 
minute  is  50,000  cu.ft.,  the  velocity  is  500  ft.  per  minute. 
What  is  the  area?     (1)  Ans.     100  sq.ft. 

2.  The  total  pressure  producing  ventilation  in  a  mine 


FORMULAS  147 

is  200  Ibs.  and  the  pressure  per  square  foot  is  2  Ibs.     What 
is  the  area?     (2)  Ans.     100  sq.ft. 

3.  If  in  an  airway  having  a  rubbing  surface  of  40,000 
sq.ft.  the  velocity  is  500  ft.  per  minute  and  the  pressure 
is  2  Ibs.  per  square  foot,  what  is  the  area?     (3) 

Ans.     100  sq.ft. 

4.  The    pressure    producing    ventilation   is    2    Ibs.    per 
square  foot,  the  velocity  is  500  ft.  per  minute,  and  the 
units  of  work  100,000.     What  is  the  area  of  the  airway?     (4) 

Ans.     100  sq.ft. 

5.  The  rubbing  surface  of  an  airway  is  40,000  sq.ft., 
the  velocity  500  ft.  per  minute,  the  units  of  work  100,000, 
and  the  quantity  of  air  passing  per  minute  is  50,000  cu.ft. 
What  is  the  area?     (6)  Ans.     100  sq.ft. 

6.  If  the  rubbing  surface  of  an  airway  is  40,000  sq.ft. 
and  50,000  cu.ft.  of  air  is  passing  under  a  total  pressure  of 
200  Ibs.,  what  is  the  area  of  the  airway?     (7) 

Ans.     100  sq.ft. 

7.  If  a  pressure  of  2  Ibs.  per  square  foot  will  produce 
a  quantity  of  air  equal  to  50,000  cu.ft.  per  minute  when 
the  rubbing  surface  is  40,000  sq.ft.,  what  is  the  area  of  the 
airway?     (8)  Ans.     100  sq.ft. 

8.  If  it  requires  a  pressure  of  2  Ibs.  per  sq.ft.  to  pass  air 
through  an  airway  of  100  sq.ft.  at  a  velocity  of  500  ft.  per 
minute,  what  is  the  horse-power?     (9)        Ans.     3.0303#. 

9.  If  it  requires  a  pressure  of  2  Ibs.  per  square  foot  to 
produce  50,000  cu.ft.  of  air  per  minute,  what  is  the  horse- 
power?    (11)  Ans.     3.0303#. 

10.  The  velocity  of  the  air  passing  through  an  airway 
is  500  ft.  per  minute.     If  the  rubbing  surface  is  40,000 
sq.ft.,  what  is  the  horse-power?     (13)         Ans.     3.0303#. 

11.  The   pressure,    area,    rubbing   surface   and  velocity 
are   respectively   2,    100,   40,000   and   500.     What   is   the 
coefficient  of  friction?     (14)  Ans.     .00000002. 


148  MINING  AND  MINE  VENTILATION 

12.  If  it  requires  2  Ibs.  per  square  foot  to  produce  50,000 
cu.ft.  of  air  per  minute,  the  velocity  of  the  air  being  500 
ft.  per  minute,  and  the  rubbing  surface  40,000  sq.ft.,  what 
is  the  coefficient  of  friction?     (16)  Ans.     .00000002. 

13.  The    horse-power  necessary  to  force  air  through  a 
mine  at  a  velocity  of  500  ft.  per  minute,  when  the  rubbing 
surface  is  40,000  sq.ft.,  is  3.0303.     What  is  the  coefficient 
of  friction?     (18)  Ans.     .00000002  nearly. 

14.  If  the  rubbing  surface  of  an  airway  is  40,000  sq.ft. 
and  the  perimeter  40  ft.,  what  is  the  length?     (19) 

Ans.     1000  ft. 

15.  The  rubbing  surface  of  an  airway  is  40,000  sq.ft. 
and  the  length  of  the  airway  is  1000  ft.     What  is  the  per- 
imeter?    (20)  Ans.     40ft. 

16.  The   pressure   producing  ventilation   is   2   Ibs.   per 
square  foot.     If  the  area  of  the  airway  is  100  sq.ft.,  what 
is  the  total  pressure?     (21)  Ans.     200  Ibs. 

17.  If  air  is  moving  at  a  velocity  of  500  ft.  per  minute 
through   an   airway   having   a  rubbing   surface   of  40,000 
sq.ft.,  what  is  the  total  pressure?     (22)        Ans.     200  Ibs. 

18.  If  it  requires  3.0303  horse-power  to  move    air  at 
a  velocity  of  500  ft.  per  minute  through  an  airway,  what 
is  the  total  pressure?     (23)  Ans.     200  Ibs.  nearly. 

19.  If   50,000   cu.ft.    of   air   pass   per   minute   through 
an  airway,  the  area  of  which  is  100  sq.ft.  and  the  rubbing 
surface  40,000  sq.ft.,  what  is  the  total  pressure?     (25) 

Ans.     200  Ibs. 

20.  If    the    following    conditions    exist    in    an    airway: 
Area  100  sq.ft.,  velocity  per  minute  500,  rubbing  surface 
40,000  sq.ft.,  what  is  the  pressure  per  square  foot?     (26) 

Ans.     2  Ibs.  per  sq.ft. 

21.  If  3.0303    horse-power    can   produce   50,000   cu.ft. 
of  air  per  minute,  what  is  the  pressure  per  square  foot?     (30) 

Ans.     2  Ibs.  nearly. 


FORMULAS  149 

22.  50,000  cu.ft.   of  air  passes  through  an  airway  at 
a  velocity  of  500  ft.  per  minute,  the  rubbing  surface  of  the 
airway  is  40,000  sq.ft.     What  is  the  pressure?     (33) 

Ans.     2  Ibs.  per  sq.ft. 

23.  The  area  of  an  airway  is  100  sq.ft.,  through  which 
50,000  cu.ft.  of  air  pass  per  minute.     If  the  rubbing  sur- 
face of  this  airway  is  40,000  sq.ft.,  what  is  the  pressure 
per  square  foot?     (34)  Ans.     2  Ibs. 

24.  If  a  pressure  of  2  Ibs.  per  square  foot  will,  in  an 
airway  having  40,000  sq.ft.   of  rubbing  surface,   produce 
a  velocity  of  500  ft.  per  minute,  what  is  the  quantity?     (36) 

Ans.     50,000  cu.ft.  per  min. 

25.  If  the  units  of  work  consumed  per  minute  equal 
100,000  and  the  pressure  2  Ibs.  per  square  inch,  what  is 
the  quantity?     (38)  Ans.     50,000  cu.ft. 

26.  The  area  of  an  airway  is  100  sq.ft.,  the  total  pres- 
sure is  200  Ibs.  and  the  rubbing  surface  40,000  sq.ft.     What 
is  the  quantity  of  air  passing  per  minute?     (39) 

Ans.     50,000  cu.ft. 

27.  If  the  area  of  an  airway  is  100  sq.ft.,  the  pressure 
per  square  foot  2  Ibs.  and  the  rubbing  surface  40,000  sq.ft., 
what  is  the  quantity  per  minute?     (39) 

Ans.     50,000  cu.ft. 

28.  The  length  of  an  airway  is  1000  ft.  and  the  per- 
imeter is  40  ft.     What  is  the  rubbing  surface?     (40) 

Ans.     40,000  sq.ft. 

29.  The  area  of  an  airway  is  100  sq.ft.,  the'  pressure 
per  square  foot  is  2  Ibs.  and  the  velocity  is  500  ft.  per  minute. 
What  is  the  rubbing  surface?     (42)       Ans.     40,000  sq.ft. 

30.  If  it  requires  a  pressure  of  2  Ibs.  per  square  foot  to 
force  50,000  cu.ft.  of  air  through  a  mine  at  a  velocity  of 
500  ft.  per  minute,  what  is  the  rubbing  surface?     (43) 

Ans.     40,000  sq.ft. 

31.  If,  in  order  to  obtain  a  velocity  of  500  ft.  per  minute, 


150  MINING  AND  MINE  VENTILATION 

3.0303    horse-power  is  required,  what  is  the  rubbing  sur- 
face?    (44)  Ans.     40,000  sq.ft.  nearly. 

32.  If  the  horse-power  producing  ventilation  is  3.0303, 
state  the  required  units  of  work  per  minute?     (46) 

Ans.     100,000  units  nearly. 

33.  State  the  units  of  power  in  foot-pounds  per  minute 
when  the  velocity  is  500  ft.  per  minute,  the  pressure  2  Ibs. 
per  square  foot  and  the  area  of  the  airway  100  sq.ft.     (47) 

Ans.     100,000  units. 

34.  State  the  units  in  foot-pounds  per   minute,  when 
the  quantity  is  50,000  cu.ft.  and  the  pressure  2  Ibs.  per 
square  foot.     (49)  Ans.     100,000  units. 

35.  The  rubbing  surface  of  an  airway  is  40,000  sq.ft., 
the  velocity  is  500  ft.   per  minute.     What  do  the  units 
equal?     (50)  Ans.     100,000  units. 

36.  What  velocity  will  be  produced  by  a  pressure  of 
2  Ibs.  per  square  foot  in  an  airway  having  a  rubbing  sur- 
face of  40,000  sq.ft.  and  an  area  of  100  sq.ft.?     (52) 

Ans.     500  ft.  vel. 

37.  The  horse-power  producing  ventilation  is  3.0303,  the 
pressure  per  square  foot  is  2  Ibs.  and  the  area  of  the  air- 
way is  100  sq.ft.     What  is  the  velocity?     (54) 

Ans.     500  ft.  nearly. 

38.  The  rubbing  surface  of  an  airway  is  40,000  sq.ft., 
the  quantity  of  air  passing  per  minute  is  50,000  cu.ft.  and 
the  pressure  per  square  foot  is  2  Ibs.     What  is  the  velocity 
per  minute?     (58)  Ans.     500  ft. 

39.  The  rubbing  surface  of  an  airway  is  40,000  sq.ft., 
the  units  of  power  in  foot-pounds  per  minute  equal  100,000. 
What  is  the  velocity  per  minute?     (60)          Ans.     500  ft. 

40.  If  the  pressure  producing  ventilation  is  2  Ibs.  per 
square  foot,  what  is  the  water  gauge?     (61) 

Ans.     .384  in. 

41.  If  the  peripheral  speed  of  a  fan  is  100  ft.  per  second 


FORMULAS  151 

and  the  weight  of  a  cubic  foot  of  air  is  .078,  what  is  the 
theoretical  water  gauge?     (62)  Ans.     4.6  ins. 

42.  What  horse-power  is  consumed  by  a  direct-current 
motor  if  the  voltage  is  250  and  the  amperes  150?     (63) 

Ans.     50.2  H.P. 


CHAPTER   XIV 
MINE  FIRES 

95.  Fires  occur  in  a  mine  by  reason  of  many  different 
causes  and  under  many  different  conditions.  The  prin- 
cipal causes  of  mine  fires  are  open  lights  setting  fire  to  dry 
timber  or  brattice  cloth,  gas  feeders  ignited  by  the  use 
of  a  long  flame  powder,  such  as  black  powder  and  dyna- 
mite, and  explosions  of  gas.  Fires  due  to  the  above  causes 
can  be  reduced  to  a  minimum  by  the  use  of  locked  safety 
lamps  and  permissible  explosives. 

During  the  ordinary  working  of  a  colliery  the  leading 
officials  should  consider  what  steps  should  be  taken  to 
avoid  mine  fires,  and  should  also  make  every  possible 
preparation  to  deal  with  a  serious  fire  should  one  occur. 
A  few  suggestions  are  given  below: 

1.  Have  a  suitable  range  of  water  pipes  from  the  sur- 
face to  the  different  sections  of  the  mine. 

2.  All    pipe    fittings,    including    connections    for    fight- 
ing  mine    fires,    should    have    standard    threads.     Serious 
delays  have    occurred  because  fire-hose  connections  could 
not  be  attached  to  the  mine  pipe  line. 

3.  A  valuable  device  for  fighting  fires  is  that  in  use 
in  the  fire-fighting  and  training  station  in  Germany.     This 
is   a   special   swing   connection  with   gate  valve   attached 
which  can  be  clamped  anywhere  on  a  pipe.     By  using  a 
ratchet-drill  a  hole  can  be  drilled  through  the  open  valve 
in  a  main  that  contains  water  under  pressure.     When  the 
hole  is  finished  the  drill  is  withdrawn  and  the  valve  closed 

152 


MINE  FIRES  153 

until  the  hose  connection  has  been  made.  When  it  is 
necessary  to  get  water  from  a  main  at  some  point  where 
there  is  no  connection  for  the  hose  this  device  is  valuable. 

4.  In  addition  to  the   safety  lamps  in   ordinary   use, 
have  in  readiness  a  supply  of  portable  electric  lamps. 

5.  Iron  doors  should  be  provided  to  close  off  the  top 
of  shaft  or  main  intake  to  prevent  smoke  going  into  the 
mine,  in  case  of  a  surface  or  shaft  fire. 

6.  Breathing   apparatus   should   be   kept   at   each   col- 
liery and  practice  drills  conducted  frequently  for  the  pur- 
pose of  training  selected  employees  in  their  use  and  estab- 
lishing confidence  in  the  apparatus. 

7.  A  telephone  system  below  ground,  with  connection 
to  the  surface,  is  an  economy  in  the  ordinary  mine  admin- 
istration and  is  highly  valuable  in  case  of  a  mine  fire,  explo- 
sion or  other  accident  when  rescue  work  is  to  be  performed. 

8.  Fire   extinguishers    have   been   successfully   used   in 
fighting  mine  fires,  and  a  supply  of  them  should  be  kept 
on  hand. 

9.  All   ventilating   fans   and   fan   drifts   should    be   so 
constructed  that  the  ventilating  current  could  be  quickly 
reversed.     If  a  fire  starts  in  the  downcast  or  main  intake 
a  quick  reversal  will  probably  save  the  miners;    however, 
reversing  the  ventilation  should  be  done  only  after  con- 
sultation and  approval  by  those  in  charge. 

SUGGESTIONS   FOR  GUIDANCE  AFTER  A  FIRE  OR 
EXPLOSION 

1.  Send  for  the  mine  inspector,   superintendent,   and, 
in  case  men   are   injured  or  entombed,  send  for  the  res- 
cue corps,  doctors  and  ambulance  corps. 

2.  In  case  of  a  shaft  mine,  if  the  ventilation  is  destroyed, 
use  a  steam  jet  in  the  upcast  shaft  and  a  water  spray  in 


154  MINING  AND  MINE  VENTILATION 

the  downcast  shaft  for  the   purpose  of  establishing  ven- 
tilation. 

3.  The  question  of  running  or  stopping  a  fan  in  case 
of  a  fire  in  the  downcast  shaft  or  in  the  main  intake,  no 
general  rule  can  be  given,  as  a  definite  knowledge  of  local 
and   general   conditions   in   each    case   will   be   necessary. 
However,  if  the  fan  is  kept  running,  the  smoke  will  be 
forced    through    the    workings    and    the    imprisoned    men 
will  likely  be  suffocated;    on  the  other  hand,  if  the  fan  be 
stopped,    fire-damp    may  accumulate    and    cause    further 
disaster.     But  from  past  experience  the  indications  seem 
to  favor  stopping  the  fan,  especially  at  mines  where  the 
men  would  have  to  travel  long  distances  through  smoke 
and  gases  given  off  by  the  fire  in  order  to  get  to  a  place 
of  safety.     As  stated,  a  general  knowledge  of  conditions 
must  be  had  before  the  actual  procedure  in  this  case  is 
definitely  determined. 

4.  Do   not   during  the   first   twenty-four   hours   spend 
time  in  recovering  the  dead  if  there  is  a  chance  to  save  life. 

5.  When  possible,  written  instructions  should  be  given 
to  the  leaders  of  the  different  exploring  parties  and  every 
member  of  the  party  should  obey  the  leader. 

6.  It  should  be  remembered  that  a  percentage  of  car- 
bon monoxide  too  small  to  be  detected  by  a  lamp  may  be 
sufficient  to  cause  death.     The  lamp  should  not  be  the 
final  guide;    mice  and  small  birds  are  useful  in  detecting 
small  percentages  of  this  gas. 

7.  When    selecting    an    exploring    party,    if    breathing 
apparatus  is  to  be  employed,  select  only  those  who  have 
been  trained  in   the  use    of  such  apparatus.     If  an  appa- 
ratus shows  the  slightest  defect  or  is  in  any  way  uncom- 
fortable it  should  not  be  used. 

8.  Never    change    the    ventilation    until    after    a    con- 
sultation is  first  had  with  the  proper  officials;    even  then 


MINE  FIRES  155 

it  should  not  be  changed  or  interfered  with  while  men  are 
in  the  mines,  unless  it  be  for  the  purpose  of  rescuing 
them. 

9.  In   case   an   apparatus  fails  to  work   satisfactorily, 
the  wearer,  accompanied  by  at  least  two  members  of  the 
party,  should  return  to  a  place  of  safety,  and  at  no  time 
during  the  preliminary  exploration  work  should  the  party 
be  away  from  safety  more  than  an  hour. 

10.  An  exploring  party  should  never,  on  the  first  visit 
to  a  mine  or  section  of  a  mine,  establish  ventilation — fires 
may   exist.     Feeders    are    usually    found    burning    at    the 
flame  zone  limit  after  an  explosion. 

•  96.  Sealing  a  Mine  Fire.— When  it  becomes  necessary 
to  seal  a  section  of  a  mine  to  enclose  a  fire,  all  persons  except 
those  needed  for  the  work  should  be  removed  from  the  mine. 
The  usual  procedure  in  connection  with  sealing  a  mine 
fire,  especially  if  the  mine  is  gaseous,  is  to  erect  temporary 
stoppings  of  brattice  cloth  or  board,  and  after  several 
hours  erect  the  permanent  stoppings  of  stone,  brick  or 
concrete. 

The  question  as  to  whether  the  return  or  intake  stop- 
ping should  be  erected  first  or  whether  both  should  be 
erected  simultaneously  has  been  freely  discussed  and 
many  varying  opinions  expressed. 

It  does  not  matter  which  stopping  is  erected  first  if 
the  mine  is  non-gaseous.  In  gaseous  mines  the  return 
stopping  should  be  erected  first,  and  to  assure  a  reasonable 
degree  of  safety  while  performing  the  work  the  stoppings 
should  be  erected  at  a  point  which  would  not  be  seriously 
disturbed  in  case  of  an  explosion. 

If  the  stopping  on  the  intake  side  of  a  fire  is  put  up 
first,  a  partial  vacuum  created  by  the  ventilating  equip- 
ment then  exists  in  the  enclosed  area  and  the  gases  gen- 
erated by  the  fire  are  drawn  away  from  it,  likewise  any 


156  MINING  AND  MINE  VENTILATION 

fire-damp  that  might  be  on  the  inside  will  move  in  the 
direction  of  the  fire,  and  an  explosion  will  likely  result. 

Methane  is  given  off  more  freely  when  the  intake  stop- 
ping is  erected  first,  because  the  pressure  on  the  working 
faces  is  reduced  to  the  extent  of  the  water  gauge  producing 
ventilation. 

In  case  of  a  fire  in  the  center  of  a  panel  of  chambers, 
and  the  return  stopping  is  erected  first,  the  gases  gener- 
ated by  the  fire  will  expand  in  all  directions,  forming  a 
zone  free  from  explosive  gases  about  the  fire,  and  any  fire- 
damp that  may  be  inside  the  fire  will  be  held  in  check  by 
reason  of  the  expansion  of  the  heated  gases  produced  by 
the  fire.  While  cases  requiring  a  reversal  of  this  method 
are  rare,  care  should  nevertheless  be  taken,  and  all  con- 
ditions that  might  affect  the  safety  of  those  engaged  in  the 
work  should  be  thoroughly  considered  before  outlining  a 
definite  plan. 

In  gaseous  mines  the  temporary  stoppings  should  not 
be  erected  gradually,  as  by  this  method  the  ventilating 
current  is  slowly  reduced  and  fire-damp  may  accumulate 
and  move  to  the  fire.  It  is  best  that  doors  be  hung  so 
that  they  will  close  by  their  own  weight;  in  this  way  a 
complete  stoppage  of  the  air  current  can  be  accomplished 
suddenly. 

97.  Effect  Produced  by  Sealing  a  Mine  Fire.— Air 
consists  by  volume  of  20.7  per  cent  of  oxygen  and  79.3 
per  cent,  chiefly  of  nitrogen.  After  a  fire  is  sealed  it  will 
burn  brightly  until  it  has  consumed  about  3  to  4  per  cent 
of  the  oxygen,  after  which  the  flame  diminishes  and  finally 
dies  away  when  the  percentage  of  oxygen  has  fallen  to 
about  13  per  cent;  then  a  smoldering  fire  exists. 

In  an  anthracite  mine  of  Pennsylvania  a  large  fire 
was  sealed.  The  territory  enclosed  by  the  stoppings 
contained  about  3,000,000  cu.ft.  of  space;  the  fire  was 


MINE  FIRES  157 

extinguished  and  the  section  reopened  in  nineteen  days. 
However,  circumstances  have  been  such  at  certain  mine 
fires  that  after  more  than  a  year  of  enclosure  fires  have 
revived.  Much  depends  upon  the  seals  and  the  depth 
of  the  fire  below  the  surface.  In  a  mine  in  Illinois  a  fire 
area  was  opened  several  months  after  enclosure;  the  area 
was  found  cool,  but  on  starting  the  ventilation  a  smol- 
dering fire  was  soon  revived.  A  close  and  thorough  inspec- 
tion should  be  made  with  breathing  apparatus  before  a 
fire  section  is  reopened. 

QUESTIONS 

1.  Why  should  permissible  explosives  only  be  used  in 
all  gaseous  mines? 

2.  What   preparation   should   be   made   at   a   mine   in 
order  to  be  in  readiness  in  case  of  a  serious  fire  or  explosion? 

3.  In  case  the  ventilating  fan  at  a  mine  is  destroyed 
and  the  ventilating  current  stops,  how  can  it  readily  be 
restored? 

4.  A  mine  in  which  300  men  are  working  is  ventilated 
by  a  fan;  locked  safety  lamps  are  used  exclusively.     A 
serious  fire  starts  in  the  main  intake;  what  would  you  do? 

5.  Should  the  leaders  of  exploring  parties  in  a  mine 
receive  written  or  verbal  instructions? 

6.  Should   the   safety   lamp   be   accepted   as   the   final 
guide  in  determining  whether  or  not  a  section  of  a  mine 
in  which  an  explosion  has  occurred  contains  carbon  mon- 
oxide? 

7.  If  while  exploring  an  unventilated  section  of  a  mine 
your  breathing  apparatus  fails  to  work  satisfactorily,  what 
should  be  done? 

8.  Should   an   exploring   party,    when   first   entering   a 
section  of  a  mine  in  which  an  explosion  occurred,  estab- 
lish ventilation  as  they  go  along? 


158 


MINING  AND  MINE  VENTILATION 


9.  If  you  were  about  to  seal  a  gaseous  section  of  a  mine 
in  order  to  smother  a  fire,   of  what  material  should  the 
first  or  temporary  stoppings  be  constructed?     Why? 

10.  If  a  fire  started  in  the  middle  of  a  panel  of  fifteen 
chambers  and  it  is  desired  to  close  off  the  fire  by  stop- 
pings,   which    stopping    should    be    constructed    first,    the 
intake  or  return,  the  mine  being  gaseous? 

11.  Does  the  erecting  of  the  intake  stopping  of  a  fire 
area  reduce  the  pressure  on  the  working  faces  in  that  sec- 
tion; if  so,  to  what  extent? 

12.  Is  it  safe  to  erect  stoppings  gradually  when  seal- 
ing a  fire  in  a  gaseous  section  of  a  mine? 

13.  Describe  the  action  of  a  fire  when  it  is  sealed. 

RULES,  FORMULAS  AND  TABLES 


Area  of  triangle 
Area  of  triangle 


=  \  (base  X  altitude)  . 


=  Vs(s  —  a)(s—  b)(s  —  c). 


s  = 


Area  of  trapezoid 
Circumference  of  circle 

Diameter  of  circle 

,«• 

Area  of  circle 

Area  of  -ellipse 
Surface  of  cylinder 

Volume  of  cylinder 
Surface  of  sphere 
Volume  of  sphere 
Surface  of  cone 

Volume  of  cone 

Area  of  sector  of  circle  = 


=  altitude  X  i  sum  of  parallel  sides. 

=  diameter  X3.1416. 

=  circumference  -$-  3.  1416. 

j  diameter  squared  X  0.7854. 

(  radius  squared  X  3.  1416. 
=  product  of  diameters  X  0.7854. 
=  circumference    of    base  X  alti- 

tude. 

=  area  of  base  X  altitude. 
=  diameter  X  circumference. 
=  diameter  cubed  X0.5236. 
=  J  (circumference  of  base  X  slant 

height)  . 

=  J(area  of  base  X  altitude)  . 
=  arcXi  radius. 


MINE  FIRES  159 

ENGLISH  MEASURES 

Length 

12  inches  =  1  foot 

3  feet  =  1  yard 
5 1  yards  =  1  rod 

4  rods  =  1  chain 
80  chains  =  1  mile 
5280  feet  =  1  mile 


144  square  inches  =  1  square  foot 
9  square  feet  =  1  square  yard 
30J  square  yards  =  1  square  rod 
160  square  rods  =  l  acre 

640  acres  =  1  square  mile 

Volume 

1728  cubic  inches  =  1  cubic  foot 
27  cubic  feet  =  1  cubic  yard 

Avoirdupois  Weight 

16  ounces  =  1  pound 
100  pounds  =  1  hundredweight 
2000  pounds  =  1  ton 
2240  pounds  =  1  long  ton 

Troy  Weight 

24  grains  =  1  pennyweight 
20  pennyweights  =  1  ounce 
12  ounces  =  1  pound 


160  MINING  AND  MINE  VENTILATION 

Measure  of  Angles 

60  seconds  =  1  minute 
60  minutes  =  1  degree 
360  degrees  =  1  circumference 
1  right  angle  =  90  degrees 

Liquids 

4  gills  =1  pint 
2  pints  =  1  quart 
4  quarts  =  1  gallon 
1  gallon  =  231  cubic  inches 
1  cubic  foot  =  nearly  1\  gallons 
1  cu.ft.  of  water  weighs  nearly  62^  pounds. 

Horse-power  of  Double-acting  Steam  Engine 
PXLXAXNXF 


H.P.= 


33,000 


P  =  gauge  pressure  at  engine; 
L  =  length  of  stroke  in  feet; 
A  =area  of  piston  in  square  inches; 
N  =  number  of  strokes  per  minute; 
F  =  factor  of  cut-off, 

.599  for  i  cut-off, 

.670  for  £  cut-off. 

ADDITIONAL  VENTILATION  FORMULAS 
klov2 


^-  l  =  — 

kov2'  kov2' 


MINE  FIRES  161 


pq  #33,000 

'  kov3 


klv2' 

K?  p 

==  -\   I    .  0  ==  o« 

\  ks  KW 

pq  #33,000 


WEIGHT  OF  ONE  CUBIC  FOOT  OF  PURE  WATER 

At  32°  F.  (freezing-point) 62.418  Ibs. 

At  39.1°  F.  (maximum  density) 62.425  Ibs. 

At  62°  F 62.355  Ibs. 

At  212°  F.  (boiling-point,  30  in.  barometer) .  59.76    Ibs. 

CHEMICAL  ANALYSIS  OF  PENNSYLVANIA  BITUMINOUS  COAL 

Moisture 1.85  per  cent. 

Volatile  matter 20.14  per  cent. 

Fixed  carbon 72.00  per  cent. 

Ash 6.01  per  cent. 

PENNSYLVANIA  ANTHRACITE 

Moisture 2.80  per  cent. 

Volatile  matter 1.16  per  cent. 

Fixed  carbon 88.21  per  cent. 

Ash 7.83  per  cent. 


162 


MINING  AND  MINE  VENTILATION 


STANDARD   HOISTING   ROPE 
Composed  of  6  Strands  and  a  Hemp  Center.     19  Wires  to  the  Strand 


Swedish.  Iron. 

Cast  Steel. 

fl 

0 

B 

g 

0 

s 

J 

rn 

li 

0 

3 

*jg   • 

0 

3 
h 

§ 

H-l 

boo 

JN 

& 

" 

S"5 

*! 

03 

d 

— 

.CO 

"S  § 

CO 

|2  vi 

.3 

""! 

fe 

38 

SH 

N.S 

I8 

£.& 

N.S 

5 

t* 

*s 

^  ^^ 

33  <n 

03  ** 

^  c^ 

02  03 

hH 

5 

Ig 

a> 

W  w 

03'^  QQ 

>• 

K  00 

^03-^  m 

>• 

d 

8 

Ml 

bo 

gl 

in 

^i3o 

11 

g| 

|ll 

il 

3 

a 
a 

•s 

§-S 

|S(S 

.S  0 

D.C 

or^ 

3s 

5 

^ 

•< 

5J 

5 

* 

Jj 

21 

8f 

11.95 

114 

22.80 

16 

228 

45.6 

10 

2£ 

71 

9.85 

95 

18.90 

15 

190 

37.9 

9^ 

2i 

71 

8.00 

78 

15.60 

13 

156 

31.2 

8| 

2 

61 

6.30 

62 

12.40 

12 

124 

24.8 

8 

H 

4.85 

48 

9.60 

10 

96 

19.2 

n 

If 

5 

4.15 

42 

8.40 

8£ 

84 

16.8 

61 

li 

41 

3.55 

36 

7.20 

71 

72 

14.4 

5! 

If 

41 

3.00 

31 

6.20 

7 

62 

12.4 

51 

11 

4 

2.45 

25 

5.00 

6£ 

50 

10.0 

5 

H 

3* 

2.00 

21 

4.20 

6 

42 

8.4 

4^ 

l 

3 

1.58 

17 

3.40 

51 

34 

6.8 

4 

1 

21 

1.20 

13 

2.60 

4| 

26 

5.2 

3^ 

t 

21 

.89 

9.7 

1.94 

4 

19.4 

3.88 

3 

I 

2 

.62 

6.8 

1.36 

3| 

13.6 

2.72 

21 

ft 

If 

.50 

5.5 

1.10 

2f 

11.0 

2.20 

U 

^ 

H 

.39 

4.4 

.88 

21 

8.8 

1.76 

ii 

11 

.30 

3.4 

.68 

2 

6.8 

1.36 

H 

1 

H 

.22 

2.5 

.50 

1-2 

5.0 

1.00 

1 

* 

i 

.15 

1.7 

.34 

1 

3.4 

.68 

1 

4 

3 

4 

.10 

1.2 

.24 

* 

2.4 

.48 

^ 

MINE  FIRES 


163 


TABLE  P 
TABLE   OF   MANILLA   ROPE 


Diam., 
Inches. 

Circ., 
Inches. 

Weight 
per  Ft., 
Pounds. 

Breaking 
Load, 
Pounds. 

Diam., 
Inches. 

Circ., 

Inches. 

Weight 
per  Ft., 
Pounds. 

Breaking 
Load, 
Pounds. 

.239 

1 

.019 

560 

1.91 

6 

1.19 

25,536 

.318 

1 

.033 

784 

2.07 

61 

1.39 

29,120 

.477 

11 

.074 

1,568 

2.23 

7 

1.62 

32,704 

.636 

2 

.132 

2,733 

2.39 

u 

1.86 

36,288 

.795 

2* 

.206 

4,278 

2.55 

8 

2.11 

39,872 

.955 

3 

.297 

6,115 

2.86 

9 

2.67 

47,040 

1.11 

3| 

.404 

8,534 

3.18 

10 

3.30 

54,208 

1.27 

4 

.528 

11,558 

3.50 

11 

3.99 

61,376 

1.43 

4i 

.668 

14,784 

3.82 

12 

4.75 

68,544 

1.59 

5 

.825 

18,368 

4.14 

13 

5.58 

75,712 

1.75 

51 

.998 

21,952 

4.45 

14 

6.47 

82,880 

NOTE. — The  strength  of  manilla  rope  is  very  variable. 
The  strength  of  pieces  from  same  coil  may  vary  25  per  cent. 
A  few  months  of  exposed  work  weakens  ropes  20  to  50 
per  cent. 

QUESTIONS 

1.  What  is  the  rubbing  surface  of  an  airway  8  ft.  6 
ins.  by  6  ft.  9  ins.  and  3000  ft.  long? 

Ans.     91,500  sq.ft. 

2.  A  circular  airway  is  15  ft.  in  diameter  and  1200  ft. 
long;    this  airway  is  equally  divided  into  two  compart- 
ments by  a  partition  (the  thickness  of  partition  may  be 
neglected).     What  is  the  rubbing  surface  in  this  airway? 

Ans.     92,548.8  sq.ft. 

3.  If  50,000  cu.ft.  of  air  is  passing  per  minute  in  an 
airway  at  a  velocity  of  8  ft.  per  second,  assuming  the  air- 
way to  be  square,  find  its  area  and  perimeter. 

Ans.     (A)  104.16  sq.ft. 
(0)     40.8  ft. 


164  MINING  AND  MINE  VENTILATION 

4.  An  airway  is  10  ft.  wide  and  6  ft.  high  and  5000  ft. 
long.     What    pressure    will    be    required    to    pass    60,000 
cu.ft.  of  air  per  minute  through  this  airway? 

Ans.     53J  Ibs.  per  sq.ft. 

5.  Explain  the  constant  5.2  used  in  connection  with 
water  gauge  and  pressure  calculations. 

6.  An  airway  is  8  ft.  by  14  ft.  and  5790  ft.  long,  the 
velocity  is  1  ft.   per  minute.     What  amount  of  pressure 
in  inches  of  water  gauge  will  be  necessary  to  overcome 
the  friction  in  this  airway?  Ans.     .0000087  in. 

7.  A  mine  airway  is  7  ft.  by  10  ft.  and  6720  ft.  long; 
if  the  water  gauge  is  2  ins.,  what  is  the  velocity? 

Ans.     399 -f-  ft.  per  min. 

8.  An  airway  is  8  ft.  wide  at  the  top  and  10  ft.  wide 
at  the  bottom,  and  7  ft.  high.     How  much  air  will  pass 
through  this  airway  if  the  anemometer  makes  165  revo- 
lutions per  minute?  Ans.     10,395  cu.ft.  per  min. 

9.  An  airway  is  of  triangular  shape,  the  sides  are  6, 
8  and  10  ft.     If  the  velocity  of  the  current  is  425  ft.  per 
minute,  what  is  the  quantity? 

RULE. — From  one-half  the  perimeter  of  the  airway 
subtract  each  side  separately;  multiply  together  the 
three  remainders  thus  found  and  half  of  the  perimeter 
and  extract  the  square  root  of  the  product.  The  result 
is  the  area  required. 

A  =  area,  a,  6,  and  c  the  three  sides  and  o  the  sum  of 
the  three  sides. 


or 


^8) (12^10)  =24  sq.ft. 
24X425  =  10,200  cu.ft.  per  min. 


MINE  FIRES  165 

10.  Explain  the  term  coefficient  of  friction  as  used  in 
mine  ventilation. 

11.  The   quantity   of   air   passing   through    a   mine   is 
60,000  cu.ft.   per  minute  and  the  water  gauge  is  2  ins. 
What  is  the  horse-power  producing  ventilation? 

Ans.     18.9  H.P. 

12.  An  airway  is  12  ft.  by  8  ft.  and  4000  ft.  long.     If 
28,800  cu.ft.  of  air  passes  through  this  airway  per  minute, 
what  is  the  pressure,  rubbing  surface  and  horse-power? 

Ans.     3  Ibs.  per  sq.ft. 
160,000  sq.ft. 
2.61  H.P. 

13.  There  are  two  splits  in  a  mine  as  follows:     Split 
A  is  4  ft.  by  12  ft.  and  6000  ft.  long;    Split  B  is  6  ft.  by 
8  ft.  and  10,000  ft.  long.     If  the  quantity  of  air  entering 
the  mine  is   10,000  cu.ft.  per  minute,  what  amount  will 
pass  through  each  split?  Ans.     (A)  5470  cu.ft. 

(B)  4530  cu.ft. 

14.  The  velocity   of  the   air  passing  through   a  mine 
is  200  ft.  per  minute  when  the  water  gauge  is  .25  in.    What 
is  the  water  gauge  when  the  velocity  is  400  ft.  per  minute? 

Ans.     1  in. 

15.  How  much  must  the  pressure  be  increased  in  order 
to  double  the  quantity  of  air?  Ans.     4  times. 

16.  If  it  requires  3  H.P.  to  produce  20,000  cu.ft.  of 
air  per  minute,  what  horse-power  will  be  required  to  pro- 
duce 40,000  cu.ft.  per  minute?  Ans.     24  H.P. 

17.  In   order   to   double   the    quantity   of   air   passing 
through  a  mine,  how   much  will  the  horse-power  have  to 
be  increased?  Ans.     8  times. 

18.  An  airway  is  6  ft.  by  7  ft.  through  which  28,000 
cu.ft.  of  air  is  passing  per  minute.     With  the  same  power 
and  length  how  much  air  will   pass  through   an  airway 
5  ft.  by  5  ft.?  Ans.     18,190  cu.ft.  per  min. 


166  MINING  AND  MINE  VENTILATION 

19.  100,000    cu.ft.    of    air    passes    through    an    airway 
6  ft.  by  5  ft.  and  10,000  ft.  long.     Three  splits  were  then 
made  as  follows:     Split  A,  6  ft.  by  6  ft.,  2000  ft.  long; 
Split  £,  6  ft.  by  5  ft.,  4000  ft.  long,  and  Split  C,  6  ft.  by 
4  ft.,  6000  ft.  long.     What  quantity  of  air  will  pass  in 
each  split  while  the  pressure  remains  the  same? 

Ans.  (A)  52,488  cu.ft. 
(B)  29,447  cu.ft. 
(CO  18,065  cu.ft. 

20.  If    an    anemometer    registers    30,000    ft.    velocity 
per  hour  in  an  airway  8  ft.  by  5  ft.,  what  quantity  of  air 
is  passing  per  minute?  Ans.     20,000  cu.ft.  per  min. 

21.  The  weight  of  a  cubic   foot   of  air  is  .0766  Ib.  and 
the  water  gauge  is   1.5  ins.     What  is  the  height  of  the 
motive  column?  Ans.     101.8+  ft. 

22.  If  155,650  cu.ft.  of  air  enters  a  mine  at  a  temper- 
ature of  32°  F.,  what  is  the  volume  leaving  the  mine,  the 
temperature  being  65°  F.?  Ans.     166,090  cu.ft. 

23.  If  32,000  cu.ft.   of  air  is  entering  a  mine  at  the 
inlet,  and  34,000  cu.ft.  leaving  it  at  the  outlet,  what  is  the 
cause  of  the  increase  in  quantity? 

24.  If  the  theoretical  water  gauge  at  a  fan  is  4  ins.  and 
the  water  gauge  actually  produced  is  2  ins.,  what  is  the 
manometric  efficiency  of  the  fan? 

Ans.     50  per  cent  manometric  efficiency. 

25.  If  while  running  at  50  revolutions  per  minute  a 
fan  delivers  60,000  cu.ft.  of  air,  how  much  air  will  be  deliv- 
ered if  the  revolutions  are  increased  to  100  per  minute? 

Ans.     120,000  cu.ft. 

26.  A    fan    running    40    revolutions    per    minute    pro- 
duced 1  in.  water  gauge.     What  will  be  the  water  gauge 
when  the  revolutions  are  60  per  minute? 

Ans.     2.25  in.  w.g. 

27.  If  with  1  in.  water  gauge  50,000  cu.ft.  of  air  are 


MINE  FIRES  167 

passing  through   a  mine   per  minute,   what   water  gauge 
will  be  required  to  pass  100,000  cu.ft.  per  minute? 

Ans.    4  in.  iy.gr. 

28.  If  it  requires  15  H.P.  to  run  a  fan  40  revolutions 
per  minute,  while  ventilating  a  mine,  what  power  will  be 
required  to  run  it  80  R.P.M.?  Ans.     120  H.P. 

29.  If  it   requires    15   H.P.    to   circulate  40,000   cu.ft. 
of  air  per  minute  through  a  mine,  what  horse-power  will 
be  required  to  circulate  80,000  cu.ft.?         Ans.     120  H.P. 

30.  If  a  fan  is  producing  150,000  cu.ft.  of  air  per  minute 
under  average  mine  conditions  with  a  2-in.  water  gauge, 
what  size  motor  or  engine  will  be  required  to  drive  it? 

Ans.     66f  H.P. 

31.  Name  the  five  causes  which  go  to  make  up  the 
total  resistance  met  with  by  the  air  while  flowing  through 
a  mine. 

32.  What  effect  has  the  sudden  contraction  and  expan- 
sion of  an  airway  on  the  quantity  of  air  passing  through 
a  mine? 

33.  An  engine  is  making  300  strokes  per  minute,  the 
area  of  the  piston  is  201  ins.     What  is  the  H.P.  if  the 
length  of  the  stroke  is  1£  ft.  and  the  mean  effective  pres- 
sure is  40  Ibs.?  Ans.     109.6  H.P. 

34.  If  a  direct-current  motor  is  using  150  amperes  and 
240  volts,  what  is  the  horse-power?         Ans.     48.25  H.P. 

35.  If  the    actual  horse-power  of  a  ventilating  equip- 
ment is  150  and  the  effective  horse-power  is  110,  what  is 
the  mechanical  efficiency?  Ans.    73J  per  cent. 

36.  If  the  rim  speed  of  a  fan  is  90  ft.  per  second,  what 
is  the  theoretical  water  gauge?  Ans.     3.7  w.g. 

37.  If  the  theoretical  water  gauge  of  a  fan  is  3  ins.  and 
the  actual  water  gauge  developed  by  the  fan  is  2  ins.,  what 
is  its  manometric  efficiency?  Ans.     66f  per  cent. 

38.  If  the    horse-power  of  a  ventilating  equipment  is 


168  MINING  AND  MINE  VENTILATION 

30,  and  from  which  only  50  per  cent  useful  effect  is  obtained, 
what  is  the  quantity  of  air  produced  if  the  water  gauge 
reading  is  2.3?  Ans.  41,388  cu.ft.  per  min. 

39.  If  the  input  horse-power  of  a  fan  engine  is  40  and 
the  output  horse-power  is  28,  what  is  the  mechanical  effi- 
ciency? Ans.     70  per  cent. 

40.  If  while  running  100  R.P.M.  a  fan  produces  40,000 
cu.ft.  of  air,  how  much  air  should  the  same  fan  produce 
when  running  125  R.P.M.?  Ans.     50,000  cu.ft. 

41.  A  fan  is  running  50  R.P.M.  and  is  producing  100,000 
cu.ft.  of  air  per  minute  at  a  water  gauge  of  1  in.  and  horse- 
power of  50.     What  will  be  the  quantity  of  air,  revolution 
of  the  fan  and  the  horse-power  of  the  engine  if  the  water 
gauge  is  increased  to  4  ins.? 

Ans.     200,000  cu.ft.  per  min. 
100  R.P.M. 
400  H.P. 

42.  A  fan  is  10  ft.  in  diameter  and  6  ft.  wide,  and  is 
running  100  R.P.M.     If  the  actual  volume  of  air  delivered 
by  the  fan  is  80,000  cu.ft.,  what  is  its  volumetric  capacity? 

Ans.     169.7  per  cent. 

43.  If  the  total  pressure  required  to  maintain  a  velocity 
of  400  ft.  per  minute  in  a  certain  airway  is  100  Ibs.,  what 
is  the  rubbing  surface?  Ans.     31,250  sq.ft. 

44.  The  length  of  an  airway  is  2000  ft.,  the  perimeter 
32  ft.     What  is  the  rubbing  surface? 

Ans.     64,000  sq.ft. 

45.  A  gangway  is  9  ft.  by  9  ft.     If  the  water  gauge 
shows  f  in.  and  the  velocity  of  the  air  is  280  ft.  per  minute, 
what  is  the  rubbing  surface?  Ans.     201,466  sq.ft. 

46.  If  a  power  of  120,000  foot-pounds  per    minute  is 
required  to  maintain  a  velocity  of  500  ft.  per  minute  in 
a  certain  airway,  what  is  the  rubbing  surface? 

Ans.     48,000  sq.ft. 


MINE  FIRES  169 

47.  80,000   cu.ft.   of  air  is   passing  through   a  certain 
airway,  the  velocity  is  300  ft.  per  minute  and  the  pressure 
equal  to  1  in.  water  gauge.     What  is  the  rubbing  surface? 

Ans.     770,370  sq.ft. 

48.  An  airway  is  of  such  length  that  it  requires  a  total 
pressure  of  140  Ibs.  to  maintain  a  velocity  of  500  ft.  per 
minute.     What  is  the  rubbing  surface? 

Ans.     28,000  sq.ft. 

49.  The  area  of  an  airway  is  36.5  ft.  and  a  pressure 
of  3  Ibs.  per  square  foot  is  required  to  maintain  a  velocity 
of  600  ft.  per  minute.     What  is  the  rubbing  surface? 

Ans.     15,208  sq.ft. 

50.  If   it   requires   30   H.P.  to  maintain  a  velocity   of 
400  ft.  per  minute  in  a  certain  airway,  what  is  the  rubbing 
surface?  Ans.     773,437  sq.ft. 

51.  A  circular  airway  has  a  radius  of  5  ft.,  its  length 
is  1000  ft.     What  is  the  rubbing  surface? 

Ans.     31,416  sq.ft. 

52.  If  the  total  pressure  required  to  produce  a  velocity 
of  400  ft.  per  minute  is  80  Ibs.,  what  will  be  the  units  of 
power?  Ans.     32,000  units. 

53.  An   airway  is  6  ft.  by  6  ft.,  the  water   gauge  is  1 
in.,   the  velocity  is   300   ft.   per  minute.     Find  the  units 
of  power  per  minute?  Ans.     56,160  units. 

54.  If  it  requires  8.5  Ibs.  pressure  per  square  foot  to 
pass  100,000  cu.ft.  of  air  per  minute  through  an  airway, 
what  are  the  foot-pounds  of  work  per  minute? 

Ans.     850,000  foot  pounds. 

55.  If  40  H.P.  is  consumed  to  ventilate  a  certain  mine, 
what  is  its  equivalent  in  units  of  work  per  minute? 

Ans.     1,320,000  units. 

56.  Find   the  foot-pounds  of  work  necessary  to  venti- 
late a  certain  mine  if  the  area  of  the  airway  is  36  ft.,  the 


170  MINING  AND  MINE  VENTILATION 

velocity  400  ft.  per  minute  and  the  pressure  10  Ibs.  per 
square  foot.  Am.     144,000  foot  pounds. 

57.  Find  the  units  of  work  necessary  to  maintain  a 
velocity  of  400  ft.  per  minute  in  an  airway,  if  the  rubbing 
surface  is  200,000  sq.ft.  Ans.     256,000  units. 

58.  An  airway  is  6  ft.  by  6  ft.  and  2000  ft.  long,  the 
quantity  of  air  passing  is   150,000.     Required,   the  units 
of  work.  Ans.     69,444,444  units. 

59.  The    pressure    producing    ventilation    is    equal    to 
1.5  in.  water  gauge,  the  area  of  the  airway  is  25  ft.  and 
the  velocity  of  the  air  is  400  ft.     What  are  the  units  of 
work?  Ans.     78,000  units. 

60.  If  the  area  of  an  airway  is  60.4  ft.,  the  velocity  is 
325  ft.  per  minute,  what  is  the  quantity? 

Ans.     19,630  cu.ft. 

61.  In  a  certain  airway  the  rubbing  surface  is  172,000 
sq.ft.  and  a  velocity  of  500  ft.  per  minute  is  maintained 
by  a  water  gauge  of  2  ins.     What  is  the  quantity? 

Ans.    41,346  cu.ft. 

62.  In  order  to  produce  a  certain  quantity  of  air,  the 
units   of  work  required   equal    125,000   and   the   pressure 
11  Ibs.     What  is  the  quantity?          Ans.'    11,363+  cu.ft. 

63.  An  airway  is  10  ft.  by  10  ft.  and  2000  ft.  long, 
through  which  a  certain  quantity  of  air  is  passing  under 
a  pressure  of  12  Ibs.  per  square  foot.     What  is  the  quan- 
tity? Ans.     86,600  cu.ft. 

64.  The  rubbing  surface  of  an  airway  is  180,000  sq.  ft. 
and  a  velocity  of  400  ft.  is  maintained  by  a  pressure  equal 
.to  1  in.  water  gauge.     What  is  the  quantity? 

Ans.     44,307+  cu.ft. 

65.  The  units  of  work  and  pressure  necessary  to  pro- 
duce a  certain  quantity  of  air  equals,  units  210,000,  pres- 
sure 8  Ibs.  per  square  foot.     What  is  the  quantity? 

Ans.     26,250  cu.ft. 


MINE  FIRES  171 

66.  If  the  water-gauge  reading  at  a  fan  is  2.3  ins.,  what 
is  the  pressure  per  square  foot? 

Ans.     11.96  Ibs.  per  sq.ft. 

67.  An  airway  has  a  rubbing  surface  of  80,000  sq.ft., 
the  velocity  is  400  ft.  per  minute,  the  quantity  of  air  pass- 
ing is  40,000  cu.ft.     What  is  the  pressure? 

Ans.    2.56  Ibs.  per  sq.ft. 

68.  If    the   horse-power    producing   ventilation   is   40, 
the  quantity  of  air  passing  through  an  airway  is  80,000 
cu.ft.,  what  is  the  pressure?          Ans.     16.5  Ibs.  per  sq.ft. 

69.  The  area  of  an  airway  is  100  sq.ft.,  the  velocity 
of  the  air  is  400  ft.     If  it  requires  20  H.P.  to  produce  this 
velocity,  what  is  the  pressure?     Ans.     16.5  Ibs.  per  sq.ft. 

70.  The  area  of  an  airway  is  80  sq.ft.,  the  rubbing 
surface  is  70,000  sq.ft.     If  the  quantity  of  air  passing  is 
100,000  cu.ft.,  what  is  the  pressure? 

Ans.     27.3  Ibs.  per  sq.ft. 

71.  If  the  total  pressure  producing  ventilation  in  an 
airway  10  ft.  by  10  ft.  is  800  Ibs.,  what  is  the  water  gauge? 

Ans.     1.53  in.  w.g. 

72.  If  it  is  required  to  pass  20,000  cu.ft.  of  air  per 
minute,  (a)  what  is  the  pressure  per  square  foot  if  6  H.P. 
is  required?    (6)  What  is  the  water  gauge  reading? 

Ans.     (a)  9.9  Ibs.  per  sq.ft. 
(6)  1.9  in.  w.g. 

73.  The  quantity  of  air  passing  per  minute  in  a  mine 
is  112,000  cu.ft.,  the  effective  power  of  the  fan  is  40  H.P. 
What  is  the  pressure?  Ans.     11.78  Ibs.  per  sq.ft. 

74.  If  it  requires  10  H.P.  to  maintain  a  velocity  of  200 
ft.  per  minute  in  an  airway  6  ft.  by  8  ft.,  what  is  the  pres- 
sure? Ans.     34.37  Ibs.  per  sq.ft. 

75.  If  it  requires  30  H.P.  to  produce  a  velocity  equal 
to  400  ft.  per  minute,  what  is  the  total  pressure? 

Ans.    2475  Ibs. 


172  MINING  AND  MINE  VENTILATION 

76.  If  the  airway   (in  Question  75)   is  square  and  its 
diagonal  is  40  ft.,  what  is  the  pressure  per  square  foot? 

Ans.     3.09  Ibs.  per  sq.ft. 

77.  If  the  units  of  work  required  to  produce  a  velocity 
of  300  ft.   per  minute  equals  660,000,  what  is  the  total 
pressure?  Ans.     2200  Ibs. 

78.  The  quantity  of  air  passing  through  an  airway  is 
36,000  cu.ft.,  the  rubbing  surface  is  78,000  sq.ft.  and  the 
area  of  the  airway  is  36  sq.ft.     What  is  the  total  pressure? 

Ans.     1560  Ibs. 

79.  If  the   units   of  work   necessary  to   force   100,000 
cu.ft.    of   air   through   an   airway   equals   1,320,000,   what 
is  the  pressure  per  square  foot? 

Ans.     13.2  Ibs.  per  sq.ft. 

80.  What  is  the  horse  power  in  Question  79? 

Ans.    40  H.P. 

81.  An  airway  is  6  ft.  by  10  ft.  and  2400  ft.  long.     If 
the  air  is  moving  at  a  velocity  of  500  ft.  per  minute,  what 
is  the  pressure  per  square  foot  and  the  total  ventilating 
pressure?  Ans.         6.4  Ibs.  per  sq.ft. 

384  Ibs.  total  pressure. 

82.  The   quantity   of   air   passing   through   an   airway 
is  100,000  cu.ft.  per  minute,  the  area  of  the  airway  is  125 
sq.ft.  and  the  rubbing  surface  is  175,000  sq.ft.     What  is 
the  pressure  per  square  foot  and  the  total  pressure  pro- 
ducing ventilation?  Ans.         17.92  Ibs.  per  sq.ft. 

2240  Ibs.  total  pressure. 

83.  An  airway  10  ft.  by  10  ft.  is  1  mile  long;  the  quan- 
tity of  air  passing  is  150,000  cu.ft.  per  minute,  the  total 
pressure  is  500  Ibs.     What  is  the  coefficient  of  friction? 

Ans.  .00000000105. 

84.  If  in  the  above  example  the  water  gauge  was  2J 
ins.,  what  would  be  the  coefficient  of  friction? 

I  Ans.  .00000000273. 


MINE  FIRES  173 

85.  If    (in    Question    83)     the    horse-power    producing 
ventilation  is  40,  what  is  the  coefficient  of  friction? 

Ans.  .0000000018. 

86.  If  it  requires  99,000  units  of  work  to  produce  a 
velocity  of  300  ft.  in  an  airway  6  ft.  by  8  ft.  and  10,000 
ft.  long,  what  is  the  coefficient  of  friction? 

Ans.     .000000013. 

87.  A  square  airway  is  2000  ft.  long,  the  water  gauge 
is  1  in.,  the  total  pressure  is  520  Ibs.,  the  quantity  of  air 
passing  is  10,000  cu.ft.     What  is  the  coefficient  of  friction? 

Ans.     .00000065. 


SUMMARY 



SOME  of  the  most  important  statements  made  in  this 
book  are  summarized  as  follows: 

The  average  height  of  the  barometer  in  the  United  States 
at  sea  level  is  29.92  ins. 

A  cubic  foot  of  dry  air  at  32°  F.  at  sea  level  weighs 
0.080728  Ib. 

The  lowest  United  States  barometer  reading  was  taken 
at  Galveston,  Texas,  during  the  year  of  flood,  when  the 
barometer  reached  28.48  ins.,  or  nearly  f  Ib.  per  square 
inch  below  normal. 

A  sudden  rise  in  the  barometer  is  nearly  as  threatening 
as  a  sudden  fall,  because  it  shows  that  the  level  is  unsteady. 

An  accurate  aneroid  will  show  the  altitude  of  a  table, 
if  lifted  from  the  floor  to  the  top  of  the  table. 

The  barometer  falls  lower  for  high  winds  than  for 
heavy  rain. 

The  temperature  of  111°  below  zero  was  taken  at  St. 
Louis,  Mo.,  at  an  altitude  of  48,700  feet. 

The  temperature  of  the  sun  is  estimated  to  be  14,072°  F. 

The  highest  known  average  monthly  temperature  ever 
observed  is  that  of  102°  F.  for  July  at  Death  Valley,  Cali- 
fornia. The  lowest  is  —60°  F.  for  January  at  Siberia. 

Absolute  zero  is  —459.4;  above  this  temperature  every- 
thing scientifically  contains  heat. 

If  every  particle  of  moisture  in  the  air  were  precipitated, 
it  would  cover  the  entire  globe  to  a  depth  of  nearly  4  ins. 

Sounds  travel  far  when  the  humidity  is  high. 

175     • 


176  SUMMARY 

Aqueous  vapor  is  a  gas  much  lighter  than  air;  its  atomic 
weight  is  9.  When  this  vapor  mixes  with  air  the  mixture 
becomes  lighter  than  dry  air. 

When  air  is  flowing  through  a  mine  there  must  be  a 
difference  in  density  between  the  intake  and  return  air. 

The  water  gauge  produced  by  a  fan  is  usually  about 
70  per  cent  of  its  theoretical  water  gauge. 

That  bituminous  coal  dust  may  be  rendered  inert  by 
the  proper  application  of  moisture  has  been  shown  both 
by  laboratory  tests  and  by  the  absence  of  explosions  at 
mines  in  which  moisture  is  present  in  the  proper  propor- 
tion to  the  quantity  of  dust  produced. 

Methane,  or  any  other  gas,  when  once  thoroughly  mixed 
with  air,  will  not  separate  from  the  mixture. 

Black  damp  is  not  carbon  dioxide  alone,  but  a  mixture 
of  carbon  dioxide  and  nitrogen. 

Lights  grow  dim  or  go  out  in  an  atmosphere  containing 
carbon  dioxide  because  of  the  low  percentage  of  oxygen 
in  the  atmosphere  and  not  because  of  the  presence  of  carbon 
dioxide. 

The  effect  on  a  person  breathing  carbon  dioxide  is  not 
always  due  to  the  carbon  dioxide  present,  but  is  some- 
times due  to  the  lack  of  oxygen. 

Air  may  be  what  is  termed  chemically  pure  and  yet 
cause  distress  if  its  temperature  and  relative  humidity 
are  high. 

An  atmosphere  must  hot  be  assumed  to  be  non-explosive 
because  it  does  not  contain  enough  oxygen  to  support  the 
combustion  of  an  oil-fed  flame. 

The  presence  of  a  fatal  percentage  of  carbon  monoxide 
is  not  indicated  by  the  lamp  flame. 

All  mine  air  contains  water  vapor,  the  proportion  de- 
pending chiefly  upon  the  temperature  of  the  air  and 
amount  of  water  present  along  the  airways. 


INDEX 


Absolute  temperature,  62 

Absolute  zero,  61 

Acceleration,  14 

Acetylene  lamp,  69 

Air  bridge,  132,  133 

Air,  composition  of,  32,  33,  72 

effect  of  expansion,  60 

height  of,  32 

humidity  of,  42,  43 

moisture  in,  76 

pressure  of,  32,  55 

properties  of,  72 

weight  of,  36 
Altitude,  table  of,  58 
Analysis,  anthracite  coal,  161 

bituminous  coal,  161 
Anemometer,  90,  91 
Aneroid  barometer,  52,  53,  54,  55 
Area  of  circle,  158 

of  ellipse,  158 

of  sector,  158 

of  trapezoid,  158 

of  triangle,  158 

Atmosphere,  composition  of,  32,  33 
Atmospheric  pressure,  32,  55,  64, 

71 

Atom,  33,  61 
Atomic  weight,  36,  37,  40 
Avoirdupois  weight,  159 

Barometer,  52,  53,  54,  55 
indications,  59 
use  of,  56,  57 


Bituminous  coal  analysis,  161 
Black  damp,  74 
Boiling,  28 
Boyle's  law,  60 
British  thermal  unit,  27 

Calcium  carbide,  68 
Calculations,  91 
Carbon  monoxide,  72 

explosive  properties,  73 
how  produced,  73 
properties  of,  72,  73 

dioxide,  73,  74 

how  produced,  74 
Carbureted  hydrogen,  36,  75 
Centigrade  scale,  28,  29 
Charles'  law,  60 
Chemical  compound,  39 

equations,  41 

properties  of  air,  72 

symbols,  39,  40 
Coal,  analysis  of,  161 

carbon  in,  161 
Coefficient  of  friction,  141 
Cohesion,  4 

Common  names  of  gases,  36 
Compressibility,  2 
Constant  force,  14 
Cost  per  horse-power,  124,  125 

Davy  safety  lamp,  70,  77 
Density,  21,  35,  45 
Dew  point,  45 

177 


178 


INDEX 


Diffusion  of  gases,  49 
Divisibility,  3 

Efficiency  of  fan,  93,  94,  95 

Elastic  limit,  3 

Elasticity,  3 

Elements,  34 
table  of,  34 

English  measure,  length,  159 
surface,  159 
volume,  159 

Entering    a    mine    after    an    ex- 
plosion, 153,  154,  155 

Ethane,  78 

Ethylene,  78 

Evaporation,  42 

Examination  questions,  146,  163 

Exchange  of  heat,  83 

Expansion  by  heat,  28,  60,  61 

Explosion,  153,  154,  155 

Extension,  1 

Fahrenheit  scale,  28,  29 
Falling  bodies,  15,  16 
Fans,  106,  107,  108,  109 
calculations  of,  91 
installation  of,  126, 127, 128, 129 
manometric  efficiency,   93,  94, 

129 
mechanical   efficiency,    93,    94, 

129 
volumetric   capacity,    95,    128, 

129 

Fire  in  mines,  152 
damp,  75 
detection  of,  76 
percentage  of  gas  in,  75 
Force,  8 
effect  of,  14 
parallelogram,  8,  9,  10 


Formulas,  36,  141,  142,  143,  144, 
145 

transposition  of,  146 
Freezing,  28 

mixture,  30 

-point,  28 

Friction,  laws  of,  96,  97,  99 
Furnace  ventilation,  106 

Gas  caps,  77 
Gases,  32,  39 

acetylene,  68,  69 

calculation  of  weight,  37,  64,  65 

density  of,  35 

diffusion  of,  49 

effect  of  temperature,  63 

general  properties  of,  72 

moving  of,  4 

occlusion  of,  71 

specific  gravity  of,  36 

table  of,  36 
Gravitation,  12 

laws  of,  12 
Gravity,  12 

Heat,  27 

capacity,  82 

measurement  of,  27,  83,  84 

specific,  82,  83 
Height  of  flame  cap,  77 
Hooke's  law,  4 
Horse-power,  124,  125,  160 

cost  of,  125 
Humidity,  absolute,  44,  45 

of  the  air,  42,  45,  48 

relative,  45,  76 

tables,  46,  47 
Hydrogen,  40 
Hydrometer,  23 
Hygrometer,  43 


INDEX 


179 


Ignition  point,  76 
Impenetrability,  2 
Indestructibility,  2 
Inertia,  3 

Installation  of  fan,  126 
Iron,  specific  gravity,  24 

Jeffrey  fan,  118,  123 
drift,  119 
table  of  capacities,  121,  122 

Lamps,  safety,  70,  71 

acetylene,  69 
Laws  of  diffusion  of  gases,  49 

of  falling  bodies,  13 

of  floating  bodies,  22 

of  friction,  96,  97,  99 

of  gravitation,  12 
Length,  units  of,  159 
Liquids  and  liquid  pressure,  19 

expansion  of,  19,  28 

measure,  160 

Manometric  efficiency,  94,  129 
Marsh  gas,  36,  75,  76,  77 

amount  in  air  to  explode,  75 

how  produced,  75 

temperature  of  ignition,  76 
Matter  defined,  1 
properties  of,  1 

Maximum  density  of  water,  28 
Mechanical  mixture,  39 
Melting-point,  table  of,  2Q 
Methane,  36,  75 
Mine  air,  samples  of,  79,  80 
Mine  fires,  152 

sealing,  155,  156,  157 

suggestions  to  avoid,  152,  153 

suggestions     to     extinguish, 

153,  154,  155 
Moisture,  42,  43 


Molecular  weight,  41 
Molecules,  33,  61,  72 
Motion,  6 

laws  of,  6,  7 
Motive  column,  130,  131 

Natural  ventilation,  105 
Newton's  laws  of  gravitation,  12 

of  motion,  6,  7 
Nitrogen,  36 

Occlusion  of  gases,  71 
Oxygen,  36 

action  on  flame,  68,  69,  70 

Parallelogram  of  forces,  8,  9,  10 
Percentage  composition  of  gases, 

41 

Physical  properties  of  air,  72 
Porosity,  2 

Pressure  of  atmosphere,  55 
defined,  88,  89 

of  gases,  62,  63,  64 

of  liquids,  9,  20 

table  of,  99,  100 
Properties  of  matter,  1,  72 

Regulators,  134,  135 
Relative  density,  20 

humidity,  76 

Resistance,  126,  127,  136,  137 
effect  of  in  mines,  137,  138 
Robinson  fan,  107,  108,  109 

table  of  volumes,  109 
Rules  and  formulas,  158,  159,  160, 
161 

Safety  lamps,  70,  71 
Saturated  water  vapor,  45 
Sirocco  fan,   109,   110,   111,    112, 
113,  114,  115,  118 


180 


INDEX 


Specific  gravity,  35,.  36 

bottle,  22 

of  liquids,  22,  23 

of  solids,  20,  21 

table  of,  24 
Specific  heat,  82,  83 

measurement  of,  83 

table  of,  83 

Splitting  of  air  currents,  132 
advantages  of,  132 
Static  pressure,  88 
Steam  jet,  106 
Sulphureted  hydrogen,  76,  78 

Table  of  specific  gravity,  24-36 

of  air  analysis,  79,  80 

of  altitudes,  58 

of  cost  per  horse-power,  125 

of  elements,  34,  36 

of  gases,  36 

of  hoisting  ropes,  162 

of  humidity,  46,  47 

of  manilla  ropes,  163 

of  melting-point,  29 

of  specific  heat,  83 

of  strength  of  ropes,  162,  163 

of  temperatures,  29 

of  theoretical  water  gauge,  120 

of  velocity  pressure,  99,  100 

of  weight,  24,  36 

of  weight  of  water  vapor,  44 
Temperature,  absolute,  62 

effect  on  volume,  60 

estimation  of,  29 


Tension,  63 
Thermometer,  27,  28 
Troy  weight,  159 

Vacuum,  106,  155 
Vapor,  44,  45 
Velocity,  8,  123 

of  air  current,  99,  123 

measurement  of,  90,  91 

pressure,  99 
Ventilation,  87,  88,  89,  104 

by  fan,  106,  107 

by  furnace,  106 

by  steam  jet,  106 

by  water  jet,  106 

how  produced,   104,   105,   106, 
107 

Water,  28 

boiling-point,  28 

expansion  of,  19,  28 

gauge,  89 

gauge  calculations,  91 

gauge,  theoretical,  94,  120,  127 

jet,  106 

maximum  density,  21 

specific  gravity,  21 

vapor,  table  of,  44 

weight  of,  20,  161 
Weather  indications,  55,  59 
Weight  of  gases,  36 
White  damp,  36,  72,  73 

Zero,  absolute,  61 


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Abbott,  A.  V.     The  Electrical  Transmission  of  Energy 8vo,  *$5  oo 

A  Treatise  on  Fuel.     (Science  Series  No.  9.) i6mo,  o  50 

—  Testing  Machines.     (Science  Series  No.  74.) i6mo,  o  50 

Adam,  P.  Practical  Bookbinding.  Trans,  by  T.  E.  Maw.iamo,    *2  50 

Adams,  H.    Theory  and  Practice  in  Designing 8vo,  *2  50 

Adams,  H.  C.     Sewage  of  Seacoast  Towns 8vo,  *2  oo 

Adams,  J.  W.     Sewers  and  Drains  for  Populous  Districts...  .8vo,  250 

Adler,  A.  A.     Theory  of  Engineering  Drawing  8vo,  *2  oo 

Principles  of  Parallel  Projecting-Line  Drawing 8vo,  *i  oo 

Aikman,  C.  M.     Manures  and  the  Principles  of  Manuring. .  .  8vo,  2  50 

Aitken,  W.     Manual  of  the  Telephone 8vo,  *8  oo 

d'Albe,  E.  E.  F.     Contemporary  Chemistry i2mo,  *i  25 

Alexander,  J.  H.     Elementary  Electrical  Engineering I2mo,  2  oo 

Allan,    W.     Strength    of    Beams    under     Transverse    Loads. 

(Science  Series  No.  19.) i6mo,  o  50 

Allan,  W.     Theory  of  Arches.     (Science  Series  No.  n.). .  i6mo, 
Allen,  H.     Modern  Power  Gas  Producer  Practice  and  Applica- 
tions   i2mo,  *2  50 

Gas  and  Oil  Engines 8vo,  *4  50 

Anderson,  J.  W.     Prospector's  Handbook i2mo,  i  50 


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Andes,  L.     Vegetable  Fats  and  Oils 8vo,  *4  oo 

—  Animal  Fats  and  Oils.     Trans,  by  C.  Salter 8vo,  *4  oo 

—  Drying  Oils,  Boiled  Oil,  and  Solid  and  Liquid  Driers . .  .8vo,  *5  oo 

—  Iron  Corrosion,   Anti-fouling  and  Anti-corrosive  Paints. 

Trans,  by  C.  Salter 8vo,     *4  oo 

Oil  Colors  and  Printers'  Ink.      Trans,   by  A.  Morris  and 

H.  Robson 8vo,     *2  50 

Treatment  of  Paper  for  Special  Purposes.     Trans,  by  C. 

Salter i2mo,     *2  50 

Andrews,  E.  S.     Reinforced  Concrete  Construction i2mo,     *i  25 

Theory  and  Design  of  Structures 8vo,      3  50 

Further  Problems  in  the  Theory  and  Design  of  Struc- 
tures   8vo,  2  50 

Andrews,    E.    S.,   and   Heywood,    H.   B.     The   Calculus   for 

Engineers    i2mo,      i  25 

Annual  Reports  on  the  Progress  of  Chemistry.  Eleven  Vol- 
umes now  ready.  Vol.  I,  1904,  to  Vol.  XI,  1914,  8vo, 
each *2  oo 

Argand,  M.     Imaginary  Quantities.     Translated  from  the  French 

by  A.  S.  Hardy.     (Science  Series  No.  52.) i6mo,      o  50 

Armstrong,  R.,  and  Idell,  F.  E.     Chimneys  for  Furnaces  and 

Steam  Boilers.     (Science  Series  No.  i.) i6mo,      o  50 

Arnold,  E.     Armature  Windings  of  Direct  Current  Dynamos. 

Trans,  by  F.  B.  DeGress 8vo,     *2  oo 

Asch,  W.,   and  Aseh,  D.     The  Silicates  in  Chemistry  and 

Commerce  8vo,    *6  oo 

Ashe,  S.  W.,  and  Keiley,  J.  D.  Electric  Railways.  Theoreti- 
cally and  Practically  Treated.  Vol.  I.  Rolling  Stock 

i2mo,  *2  50 

Ashe,  S.  W.  Electric  Railways.  Vol.  II.  Engineering  Pre- 
liminaries and  Direct  Current  Sub-Stations i2mo,  *2  50 

Electricity:  Experimentally  and  Practically  Applied. 

i2mo,  *2  oo 

Ashley,  R.  H.    Chemical  Calculations i2mo,    *i  oo 

Atkinson,  A.  A.    Electrical  and  Magnetic  Calculations.  .8 vo,    *i  50 

Atkinson,  J.  J.  Friction  of  Air  in  Mines.  (Science  Series 

No.  14.) i6mo,  o  50 

Atkinson,  J.  J.,  and  Williams,  E.  H.,  Jr.  Gases  Met  with  in 

Coal  Mines.  (Science  Series  No.  13.)-. i6mo,  o  50 


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Atkinson,  P.     The  Elements  of  Electric  Lighting i2mo,  i  50 

The  Elements  of  Dynamic  Electricity  and  Magnetism.  i2mo,  2  oo 

Atkinson,  P.     Power  Transmitted  by  Electricity i2mo,  2  oo 

Auchincloss,  W.  S.     Link  and  Valve  Motions  Simplified 8 vo,  *  i  50 

Austin,  E.    Single  Phase  Electric  Railways 4to,  *s  oo 

Ayrton,  H.     The  Electric  Arc 8vo,  *5  oo 

Bacon,  F.  W.     Treatise  on  the  Richards  Steam-Engine  Indica- 
tor   1 2mo,  i  oo 

Bailes,  G.  M.  Modern  Mining  Practice.  Five  Volumes. 8 vo,  each,  3  50 

Bailey,  R.  D.     The  Brewers'  Analyst 8vo,  *5  oo 

Baker,  A.  L.     Quaternions i2mo,  *i  25 

Thick-Lens  Optics i2mo,  *i  50 

Baker,  Benj.     Pressure  of  Earthwork.     (Science  Series  No.  56.) 

i6mo, 

Baker,  I.  0      Levelling.     (Science  Series  No.  91.) i6mo,  o  50 

Baker,  M.  N.    Potable  Water.     (Science  Series  No.  61) .  i6mo,  o  50 
—  Sewerage  and  Sewage  Purification.     (Science  Series  No.  18.) 

i6mo,  o  50 
Baker,    T.    T.       Telegraphic    Transmission    of    Photographs. 

i2mo,  *i  25 

Bale,  G.  R.    Modern  Iron    Foundry  Practice.    Two  Volumes. 

i2tno. 

Vol.    I.  Foundry  Equipment,  Material  Used *2  50 

Vol.  II.  Machine  Moulding  and  Moulding  Machines *i  50 

Ball,  J.  W.     Concrete  Structures  in  Railways 8vo,  *2  50 

Ball,  R.  S.     Popular  Guide  to  the  Heavens 8vo,  *4  50 

Natural  Sources  of  Power.     (Westminster  Series) 8vo,  *2  oo 

Ball,  W.  V.     Law  Affecting  Engineers 8vo,  *3  50 

Bankson,  Lloyd.     Slide  Valve  Diagrams.     (Science  Series  No. 

108.) i6mo,  o  50 

Barba,  J.     Use  of  Steel  for  Constructive  Purposes i2mo,  i  oo 

Barham,   G.  B.    Development  of  the  Incandescent  Electric 

Lamp    8vo  *2  oo 

Barker,  A.     Textiles  and    Their    Manufacture.     (Westminster 

Series) 8vo,  2  oo 

Barker,  A.  F.,  and  Midgley,  E.    Analysis  of  Textile  Fabrics, 

8vo,    3  oo 

Barker,  A.  H.    Graphic  'Methods  of  Engine  Design — i2mo,  *i  50 
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Barnard,  J.  H.    The  Naval  Militiaman's  Guide.  .  i6mo,  leather,  i  oo 
Barnard,  Major  J.  G.     Rotary  Motion.     (Science  Series  No.  90.) 

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Barrus,  G.  H.     Boiler  Tests 8vo,  *3  oo 

Engine  Tests 8vo,  *4  oo 

The  above  two  purchased  together *6  oo 

Barwise,  S.     The  Purification  of  Sewage i2mo,  3  50 

Baterden,  J.  R.     Timber.     (Westmenster  Series) 8vo,  *2  oo 

Bates,  E.  L.,  and  Charlesworth,  F.     Practical  Mathematics  and 

Geometry  for  Technical  Students i2mo, 

Part   I.    Preliminary  and  Elementary  Course *i  50 

Part  II.    Advanced  Course *i  50 

Practical  Mathematics *i  50 

Practical  Geometry  and  Graphics *2  oo 

Batey,  J.    The  Science  of  Works  Management. ....... .i2mo,  *i  25 

Beadle,  C.  Chapters  on  Pa permaking.  Five  Volumes.  i2mo,  each,  *2  oo 

Beaumont,  R.     Color  in  Woven  Design 8vo,  f  *6  oo 

Finishing  of  Textile  Fabrics 8vo,  *  *4  oo 

Bechhold,  H.  Colloids  in  Biology  and  Medicine.  Trans,  by  J.  G. 

Bullowa (In  Press.} 

Bedell,  F.,  and  Pierce,  C.  A.     Direct  and  Alternating  Current 

Manual 8vo,  *2  oo 

Beech,  F.     Dyeing  of  Cotton  Fabrics 8 vo,  *3  oo 

Dyeing  of  Woolen  Fabrics 8vo,  *3  50 

Beckwith,  A.     Pottery 8 vo,  paper,  o  60 

Beggs,  G.  E.    Stresses  in  Railway  Girders  and  Bridges ....  (In  Press.) 

Begtrup,  J.     The  Slide  Valve 8 vo,  *2  oo 

Bender,  C.  E.     Continuous  Bridges.     (Science  Series  No.  26.) 

i6mo,  o  50 

Proportions  of  Pins  used  in  Bridges.  (Science  Series  No.  4.) 

i6mo,  o  50 

Bengough,  G.-D.    Brass.     (Metallurgy  Series) (In  Press.) 

Bennett,  H.G.      The  Manufacture  of  Leather 8vo,  *4  50 

Bernthsen,  A.     A  Text-book  of  Organic  Chemistry.     Trans,  by 

G.  M'Gowan 12010,  *2  50 

Berry,  W.  J.     Differential  Equations  of  the  First  Species. 

i2mo  (In  Preparation.) 
Bersch,  J.     Manufacture  of  Mineral  and  Lake  Pigments.     Trans. 

by  A.  C.Wright 8vo,  *s  oo 


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Bertin,  L.  E.     Marine  Boilers.     Trans,  by  L.  S.  Robertson.  .8vo,  5  oo 

Beveridge,  J.     Papennaker's  Pocket  Book 121210,  *4  oo 

Binnie,  Sir  A.     Rainfall  Reservoirs  and  Water  Supply.  .8vo,  *3  oo 

Binns,  C,  F.     Manual  of  Practical  Potting 8vo,  *7  50 

The  Potter's  Craft i2rao,  *2  oo 

Birchmore,  W.  H.    Interpretation  of  Gas  Analysis i2mo,  *i  25 

Blaine,  R.  G.    The  Calculus  and  Its  Applications i2mo,  *i  50 

Blake,  W.  H.     Brewer's  Vade  Mecum 8vo,  *4  oo 

Blasdale,   W.    C.     Quantitative    Chemical  Analysis.  ..  .i2mo,  *2  50 

Bligh,  W.  G.    The  Practical  Design  of  Irrigation  Works.  .8vo,  *6  oo 

Bloch,  L.     Science  of  Illumination 8vo,  *2  50 

Blok,  A.    Illumination  and  Artificial  Lighting i2mo,  *i  25 

Blucher,  H.     Modern  Industrial  Chemistry.     Trans,  by  J.  P. 

Millington    8vo,  *7  50 

Blyth,  A.  W.    Foods:  Their  Composition  and  Analysis.  ..Svo,  7  50 

Poisons:   Their  Effects  and  Detection 8vo,  7  50 

Bockmann,  F.     Celluloid i2mo,  *2  50 

Bodmer,  G.  R.    Hydraulic  Motors  and  Turbines i2mo,  5  oo 

Boileau,  J.  T.  Traverse  Tables Svo,  5  oo 

Bonney,  G.  E.    The  Electro-plater's  Handbook i2mo,  i  20 

Booth,  N.    Guide  to  Ring-Spinning  Frame i2ino,  *i  25 

Booth,  W.  H.    Water  Softening  and  Treatment Svo,  *2  50 

Superheaters  and  Superheating  and  their  Control.  ..8vo,  *i  50 

Bottcher,  A.    Cranes:  Their  Construction,  Mechanical  Equip- 
ment and  Working.    Trans,  by  A.  Tolhausen. ..  .4to,  *io  oo 
Bottler,  M.     Modern  Bleaching  Agents.    Trans,  by  C.  Salter. 

1 2 mo,  *2  50 

Bottone,  S.  R.     Magnetos  for  Automobilists i2mo,  *i  oo 

Boulton,  S.  B.    Preservation  of  Timber.     (Science  Series  No. 

82.) i6mo,  050 

Bourcart,  E.    Insecticides,  Fungicides  and  Weedkillers . . .  Svo,  *4  50 
Bourgougnon,  A.    Physical  Problems.  (Science  Series  No.  113.) 

i6mo,  o  50 
Bourry,    E.      Treatise    on    Ceramic    Industries.      Trans,    by 

A.  B.  $earle     Svo,  *s  oo 

Bowie,  A.  J.,  Jr.  A  Practical  Treatise  on  Hydraulic  Mining. Svo,  5  oo 

Bowles,  0.  Tables  of  Common  Rocks.    (, Science  Series.)  .i6mo,  050 


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Bowser,  E.  A.  Elementary  Treatise  on  Analytic  Geometry.  i2mo,  i  75 

—  Elementary   Treatise   on   the   Differential    and   Integral 

Calculus    i2mo,  2  25 

Bowser,  E.  A.    Elementary  Treatise  on  Analytic  Mechanics, 

i2mo,  3  oo 

—  Elementary   Treatise   on   Hydro-mechanics i2mo,  2  50 

—  A  Treatise  on  Roofs  and  Bridges *2  25 

Boycott,  G.  W.  M.     Compressed  Air  Work  and  Diving.  .8vo,  *4  oo 

Bragg,   E.  M.     Marine   Engine  Design i2mo,  *2  oo 

—  Design  of  Marine  Engines  and  Auxiliaries ,(In  Press.) 

Brainard,  F.  R.    The  Sextant.    (Science  Series  No.  ioi.).i6mo, 

Brassey's  Naval  Annual  for  1911 8vo,  *6  oo 

Brew,  W.     Three-Phase   Transmission 8vo,  *2  oo 

Briggs,  R.,  and  Wolff,  A.  R.    Steam-Heating.    (Science  Series 

No.  67.)  i6mo,  o  50 

Bright,  C.  The  Life  Story  of  Sir  Charles  Tilson  Bright.  .8vo,  *4  50 
Brislee,  T.  J.  Introduction  to  the  Study  of  Fuel.  (Outlines 

of  Industrial  Chemistry.) 8vo,  *3  oo 

Broadfoot,  S.  K.  Motors  Secondary  Batteries.  (Installation 

Manuals  Series.)  i2mo,  *o  75 

Broughton,  H.  H.  Electric  Cranes  and  Hoists *g  oo 

Brown,  G.  Healthy  Foundations.  (Science  Series  No.  80.). i6mo,  o  50 

Brown,  H.  Irrigation 8vo,  *5  oo 

Brown,  Wm.  N.  The  Art  of  Enamelling  on  Metal i2mo,  *i  oo 

—  Handbook  on  Japanning  and  Enamelling i2mo,  *i  50 

—  House   Decorating  and   Painting i2mo,  *i  50 

—  History   of   Decorative   Art i2mo,  *i  25 

Dipping,    Burnishing,    Lacquering    and    Bronzing    Brass 

Ware i2mo,  *i  oo 

—  Workshop  Wrinkles 8vo,  *i  oo 

Browne,  R.  E.    Water  Meters.    (Science  Series  No.  8i.).i6mo,  o  50 

Bruce,  E.  M.     Pure  Food  Tests i2mo,  *i  25 

Bruhns,  Dr.     New  Manual  of  Logarithms 8vo,  cloth,  2  oo 

Half  morocco,  2  50 
Brunner,  R.  Manufacture  of  Lubricants,  Shoe  Polishes  and 

Leather  Dressings.     Trans,  by  C.  Salter 8vo,  *s  oo 


8 

Buel,  R.  H.    Safety  Valves.     (Science  Series  No.  21.)  .  . .  i6mo,  o  50 
Burley,   G.   W.     Lathes,   Their  Construction   and   Operation, 

121110,  I     25 

Burstall,  F.  W.    Energy  Diagram  for  Gas.    With  text.  ,.8vo,  *i  50 

Diagram  sold  separately ''i  oo 

Burt,  W.  A.    Key  to  the  Solar  Compass i6mo,  leather,  2  50 

Buskett,  E.   W.     Fire   Assaying i2mo,  *i  25 

Butler,  H.  J.    Motor  Bodies  and  Chasis 8vo,  *2  50 

Byers,    H.    G.,    and    Knight,    H.    G.      Notes    on    Qualitative 

Analysis    8vo,  *i  50 

Cain,  W.    Brief  Course  in  the*  Calculus 12  mo,  *i  75 

Elastic  Arches.      (Science  Series  No.  48.) i6mo,  o  50 

Maximum  Stresses.     (Science  Series  No.  38.) i6mo,  o  50 

Practical  Dsigning  Retaining  of  Walls.    (Science  Series 

No.  3.)    i6mo,  050 

Theory  of  Steel-concrete  Arches  and  of  Vaulted  Struc- 
tures.    (Science  Series.) i6mo,  o  50 

Theory  of   Voussoir  Arches.      (Science   Series  No.   12.) 

i6mo,  o  50 

Symbolic  Algebra.     (Science  Series  No.  73.) i6mo,  o  50 

Carpenter,  F.  D.     Geographical  Surveying.     (Science  Series 

No.  37.)   i6mo, 

Carpenter,   R.    C.,    and   Diederichs,    H.      Internal-Combustion 

Engines    8vo,  *s  oo 

Carter,  E.  T.    Motive  Power  and  Gearing  for  Electrical  Ma- 
chinery     8vo,  3  50 

Carter,  H.  A.    Ramie  (Rhea),  China  Grass .i2mo,  *2  oo 

Carter,  H.  R.    Modern  Flax,  Hemp,  and  Jute  Spinning. .   8vo,  *3  oo 

Bleaching,  Dyeing  and  Finishing  of  Fabrics Jvo,  *i  oo 

Cary,  E.  R.    Solution  of  Railroad  Problems  With  the  Use  of 

the  Slide  Rule i6mo,  *i  oo 

Cathcart,  W.  L.    Machine  Design.    Part  I.    Fastenings .  . .  8vo,  *3  oo 
Cathcart,   W.   L.,   and   Chaffee,   J.   I.     Elements   of   Graphic 

Statics  and  General   Graphic  Methods 8vo,  *3  oo 

Short  Course   in  Graphic  Statics i2mo,  *i  50 


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Caven,  R.  M.,  and  Lander,  G.  D.    Systematic  Inorganic  Chem- 
istry     1 2mo,  *2  oo 

Chalkley,  A.  P.    Diesel  Engines 8vo,  *3  oo 

Chambers'  Mathematical  Tables 8vo,  i  75 

Chambers,  G.  F.    Astronomy i2mo,  *i  50 

Charpentier,   P.     Timber 8vo,  *6  oo 

Chatley,  H.    Principles  and  Designs  of  Aeroplanes.    (Science 

Series.)    i6mo,  o  50 

How  to  Use  Water  Power i2mo,  *i  oo 

Child,   C.  D.     Electric   Arcs 8vo,  *2  oo 

Child,  C.  T.    The  How  and  Why  of  Electricity i2mo,  i  oo 

Christian,  M.    Disinfection  and  Disinfectants 121110,  *2  oo 

Christie,  W.   W.     Boiler-waters,   Scale,   Corrosion,  Foaming, 

8vo,  *3  oo 

Chimney  Design  and  Theory 8vo,  *3  oo 

Furnace   Draft.      (Science   Series.) i6mo,  o  50 

Water,  Its  Purification  and  Use  in  the  Industries.  .8vo, 

Church's  Laboratory  Guide.    Rewritten  by  Edward  Kinch .  8vo,  *2  50 

Clapperton,  G.     Practical  Papermaking 8vo,  250 

Clark,  A.  G.     Motor  Car  Engineering. 

Vol.   I.     Construction   8vo,  *3  oo 

Vol.  II.     Design (In   Press.) 

Clark,  C.  H.     Marine  Gas  Engines i2mo,  *i  50 

Clark,  J.  M.    New  System  of  Laying  Out  Railway  Turnouts, 

121110,  i  oo 
Clarke,  J.  W.,  and  Scott,  W.    Plumbing  Practice. 

Vol.      I.    Lead  Working  and  Plumbers'  Materials ..  8vo,  *4  oo 

Vol.    II.    Sanitary  Plumbing  and  Fittings (In  Press.) 

Vol.  III.    Practical  Lead  Working  on  Roofs (In  Press.) 

Clerk,    D.,   and   Idell,   F.    E.     Theory    of    the   Gas   Engine. 

(Science  Series  No.  62.) i6mo,  o  50 

Clevenger,   S.   R.     Treatise   on   the  Method   of   Government 

Surveying   i6mo,  mor.,  2  50 

Clouth,  F.     Rubber,  Gutta-Percha,  and  Balata 8vo,  *5  oo 

Cochran,  J.    Treatise  on  Cement  Specifications 8vo,  *i  oo 

Concrete  and  Reinforced  Concrete  Specifications 8vo,  *2  50 


10  D.  VAN  NOSTRAND  COMPANY'S  SHORT-TITLE  CATALOG 

Coffin,  J.  H.  C.    Navigation  and  Nautical  Astronomy.  .i2mo,  *s  50 
Colburn,  Z.,  and  Thurston,  R.  H.     Steam  Boiler  Explosions. 

(Science  Series  No.  2.) i6mo,  o  50 

Cole,  R.  S.    Treatise  on  Photographic  Optics i2mo,  i  50 

Coles-Finch,  W.     Water,  Its  Origin  and  Use 8vo,  *5  oo 

Collins,  J.  E.     Useful  Alloys  and  Memoranda  for  Goldsmiths, 

Jewelers i6mo,  o  50 

Collis,  A.  G.    High  and  Low  Tension  Switch-Gear  Design. 8vo,  *3  50 

Switchgear.     (Installation  Manuals  Series.) i2mo,  o  50 

Coombs,  H.  A.     Gear  Teeth.     (Science  Series  No.  120). .  .i6mo,  o  50 

Cooper,  W.  R.     Primary  Batteries 8vo,  *4  oo 

Copperthwaite,  W.  C.     Tunnel  Shields 4to,  ~g  oo 

Corey,  H.  T.     Water  Supply  Engineering 8vo  (In  Press.) 

Corfield,  W.  H.  Dwelling  Houses.  (Science  Series  No.  50.)  i6mo,  o  50 

Water  and  Water-Supply.     (Science  Series  No.  17.). .  i6mo,  j  50 

Cornwall,  H.  B.     Manual  of  Blow-pipe  Analysis 8vo,  *2  50 

Cowell,  W.  B.     Pure  Air,  Ozone,  and  Water i2mo,  *2  oo 

Craig,  J.  W.,  and  Woodward,  W.  P.    Questions  and  Answers 

about  Electrical  Apparatus i2mo,  leather,  i  50 

Craig,  T.     Motion  of  a  Solid  in  a  Fuel.     (Science  Series  No.  49.) 

i6mo,  o  50 
Wave  and  Vortex  Motion.     (Science  Series  No.  43.) .  i6mo,  o  50 

Cramp,  W.     Continuous  Current  Machine  Design 8vo,  *2  50 

Greedy,  F.  Single-Phase  Commutator  Motors 8vo,  *2  oo 

Crocker,  F.  B.     Electric  Lighting.     Two  Volumes.     8vo. 

Vol.   I.     The  Generating  Plant 3  oo 

Vol.  II.    Distributing  Systems  and  Lamps 

Crocker,  F  B.,  and  Arendt,  M.     Electric  Motors 8vo,  *2  50 

and  Wheeler,  S.  S.    The  Management  of  Electrical  Ma- 
chinery  i2mo,  *i  oo 

Cross,  C.  F.,  Bevan,  E.  J.,  and  Sindall,  R.  W.     Wood  Pulp  and 

Its  Applications.     (Westminster  Series.) 8vo,  *2  oo 

Crosskey,  L.  R.     Elementary  Prospective 8 vo,  i  oo 

Crosskey,  L.  R.,  and  Thaw,  J.     Advanced  Perspective 8vo,  i  50 

Culley,J.  L.    Theory  of  Arches.    (Science  Series  No.  87.).  i6mo,  050 

Dadourian,  H.  M.    Analytical  Mechanics 8vo.  *s  oo 

Danby,  A.     Natural  Rock  Asphalts  and  Bitumens 8vo,  *2  50 


D.  VAN  NOSTRAND  COMPANY'S  SHORT-TITLE  CATALOG    11 

Davenport,  C.     The  Book.     (Westminster  Series.) 8vo,  *2  oo 

Davey,  N.    The  Gas  Turbine 8vo,  *4  oo 

Da  vies,  F.  H.      Electric  Power  and  Traction 8vo,  *2  oo 

Foundations  and  Machinery  Fixing.   (Installation  Manuals 

Series.) i6mo,  i  oo 

Dawson,  P.     Electric  Traction  on  Railways 8vo,  *g  oo 

Deerr,  N.     Cane  Sugar 8vo,  7  oo 

Deite,  C.     Manual  of  Soapmaking.     Trans,  by  S.  T.  King.  -4to,  *5  oo 
De  la  Coux,  H.     The  Industrial  Uses  of  Water.     Trans,  by  A. 

Morris 8 vo,  *4  50 

Del  Mar,  W.  A.     Electric  Power  Conductors 8 vo,  *2  oo 

Denny,  G.  A.     Deep-Level  Mines  of  the  Rand 410,  *io  oo 

—  Diamond  Drilling  for  Gold *5  oo 

De  Roos,  J.  D.  C.     Linkages.     (Science  Series  No.  47.). . .  i6mo,  o  50 

Derr,  W.  L.     Block  Signal  Operation Oblong  i2mo,  *i  50 

Maintenance  of  Way  Engineering (In  Preparation.) 

Desaint,  A.     Three  Hundred  Shades  and  How  to  Mix  Them. 

8vo,  8  oo 

De  Varona,  A.     Sewer  Gases.     (Science  Series  No.  55.)...  i6mo,  o  50 
Devey,  R.  G.     Mill  and  Factory  Wiring.     (Installation  Manuals 

Series.) i2mo,  *i  oo 

Dibdin,  W.  J.     Purification  of  Sewage  and  Water 8vo,  6  50 

Dichman,  C.    Basic  Open-Hearth  Steel  Process 8vo,  *3  50 

Dieterich,  K.    Analysis  of  Resins,  Balsams,  and  Gum  Resins 

8vo,  *3  oo 
Dinger,  Lieut.  H.  C.     Care  and  Operation  of  Naval  Machinery 

i2mo.  *2  oo 

Dixon,  D.  B.     Machinist's  and  Steam  Engineer's  Practical  Cal- 
culator   i6mo,  mor.,  i  25 

Doble,  W.  A.    Power  Plant  Construction  on  the  Pacific  Coast.  (In  Press.) 

Dommett,  W.  E.     Motor  Car  Mechanism i2mo,  *i  25 

Dorr,  B.  F.    The  Surveyor's  Guide  and  Pocket  Table-book. 

i6mo,  mor.,  2  oo 
Draper,   C.   H.     Elementary   Text-book   of   Light,    Heat  and 

Sound i2mo,  i  oo 

Draper,  C.  H.      Heat  and  the  Principles  of  Thermo-dynamics, 

New  and  Revised   Edition i2ino,  2  oo 


12 


D.  VAN  N08TRAND  COMPANY  S  SHORT-TITLE  CATALOG 


Dron,  R.  W.  Mining  Formulas i2mo,  i  oo 

Dubbel,  H.  High  Power  Gas  Engines 8vo,  *s  oo 

Duckwall,  E.  W.  Canning  and  Preserving  of  Food  Products  .8 vo,  *s  oo 
Dumesny,  P.,  and  Noyer,  J.  Wood  Products,  Distillates,  and 

Extracts 8 vo,  *4  50 

Duncan,  W.  G.,  and  Penman,  D.  The  Electrical  Equipment  of 

Collieries 8 vo,  *4  oo 

Dunstan,  A.  E.,  and  Thole,  F.  T.  B.  Textbook  of  Practical 

Chemistry i2mo,  *i  40 

Duthie,  A.  L.  Decorative  Glass  Processes.  (Westminster 

Series) 8vo,  *2  oo 

Dwight,  H.  B.  Transmission  Line  Formulas 8vo,  *2  oo 

Dyson,  S.  S.  Practical  Testing  of  Raw  Materials 8 vo,  *5  oo 

and  Clarkson,  S.  S.  Chemical  Works 8vo,  *7  50 

Eccles,  W.  H.  Wireless  Telegraphy  and  Telephony. ...  (In  Press.) 
Eck,  J.  Light,  Radiation  and  Illumination.  Trans,  by  Paul 

Hogner 8vo,  *2  50 

Eddy,  H.  T.     Maximum  Stresses  under  Concentrated  Loads, 

8vo,  i  50 

Edelman,  P.    Inventions  and  Patents i2mo,   (In  Press.) 

Edgcumbe,  K.     Industrial  Electrical  Measuring  Instruments . 

8vo. 
Edler,  R.    Switches  and  Switchgear.    Trans,  by  Ph.  Laubach. 

8vo,  *4  oo 

Eissler,  M.*  The  Metallurgy  of  Gold 8vo,  7  50 

The  Metallurgy  of  Silver 8  vo,  4  oo 

The  Metallurgy  of  Argentiferous  Lead 8vo,  5  oo 

A  Handbook  of  Modern  Explosives 8vo,  5  oo 

Ekin,  T.  C.      Water  Pipe  and    Sewage    Discharge  Diagrams 

folio,  *3  oo 

Electric  Light  Carbons,  Manufacture  of 8vo,  i  oo 

Eliot,  C.  W.,  and  Storer,  F.  H.    Compendious  Manual  of  Qualita- 
tive Chemical  Analysis i2mo,  *i  25 

Ellis,  C.     Hydrogenation  of  Oils 8vo,  *4  oo 

Ellis,  G.    Modern  Technical  Drawing 8vo,  *2  oo 

Ennis,  Wm.  D.     Linseed  Oil  and  Other  Seed  Oils   8vo,  *4  oo 

Applied  Thermodynamics 8vo,  *4  50 

• Flying  Machines  To-day i2mo,  *i  50 


D.  VAN  NOSTRAND  COMPANY'S  SHORT-TITLE  CATALOG     13 

Vapors  for  Heat  Engines i2mo,  *i  oo 

Erfurt,  J.    Dyeing  of  Paper  Pulp.    Trans,  by  J.  Hubner.  .8vo. 

Ermen,  W.  F.  A.     Materials  Used  in  Sizing i2mo,  *2  oo 

Evans,  C.  A.     Macadamized  Roads (In  Press.) 

Ewing,  A.  J.     Magnetic  Induction  in  Iron 8vo,  *4  oo 

Fairie,  J.     Notes  on  Lead  Ores i2mo,  *i  oo 

Notes  on  Pottery  Clays i2mo,  *i  50 

Fairley,  W.,  and  Andre,  Geo.  J.     Ventilation  of  Coal  Mines. 

(Science  Series  No.  58.) i6mo,  o  50 

Fairweather,  W.  C.     Foreign  and  Colonial  Patent  Laws  . .  .8vo,  *3  oo 

Fanning,  T.  T.     Hydraulic  and  Water-supply  Engineering. 8 vo,  *5  oo 

Fay,  I.  W.    The  Coal-tar  Colors ; 8vo,  *4  oo 

Fernbach,  R.  L.    Glue  and  Gelatine 8vo,  *3  oo 

Chemical  Aspects  of  Silk  Manufacture i2mo,  *i  oo 

Fischer,  E.     The  Preparation  of  Organic  Compounds.     Trans. 

by  R.  V.  Stanford 1 2mo,  *i  25 

Fish,  J.  C.  L.     Lettering  of  Working  Drawings Oblong  80,  i  oo 

Fisher,  H.  K.  C.,  and  Darby,  W.  C.     Submarine  Cable  Testing. 

8vo,  *3  50 
Fleischmann,  W.     The  Book  of  the  Dairy.     Trans,  by  C.  M. 

Aikman 8vo,  4  oo 

Fleming,    J.    A.     The    Alternate-current    Transformer.     Two 

Volumes 8vo, 

Vol.    I.     The  Induction  of  Electric  Currents *5  oo 

Vol.  II.     The  Utilization  of  Induced  Currents *5  oo 

Propagation  of  Electric  Currents 8vo,  *3  oo 

—  A  Handbook  for  the  Electrical  Laboratory  and  Testing 

Room.     Two  Volumes 8vo,  each,  *5  oo 

Fleury,  P.     White  Zinc  Paints I2mo,  *2  50 

Flyrni,  P.  J.    Flow  of  Water.     (Science  Series  No.  84.)  .i6mo,  o  50 

Hydraulic  Tables.    (Science   Series   No.  66.) i6mo,  o  50 

Forgie,  J.    Shield  Tunneling 8vo.  (In  Press.) 

Foster,  H.  A.     Electrical  Engineers'  Pocket-book.     (Seventh 

Edition.) i2mo, leather,  5  oo 

Engineering  Valuation  of  Public  Utilities 8vo,  *3  oo 

Handbook  of  Electrical  Cost  Data. 8vo.    (In  Press) 

Fowle,  F.  F.     Overhead  Transmission  Line  Crossings  ..  .  .i2mo,  *i  50 
The  Solution  of  Alternating  Current  Problems 8vo  (In  Press.) 


14     D.  VAN  NOSTRAND  COMPANY'S  SHORT-TITLE  CATALOG 

Fox,  W.  G.     Transition  Curves.     (Science  Series  No.  no.). i6mo,  050 
Fox,  W.,  and  Thomas,  C.  W.     Practical  Course  in  Mechanical 

Drawing i2mo,  i  25 

Foye,  J.  C.     Chemical  Problems.     (Science  Series  No.  69.). i6mo,  o  50 
—  Handbook   of    Mineralogy.      (Science    Series    No.   86.). 

i6mo,  o  50 

Francis,  J.  B.     Lowell  Hydraulic  Experiments 4to,  15  oo 

Franzen,  H.    Exercises  in  Gas  Analysis 12010,  *i  oo 

French,  J.  W.     Machine  Tools,     a  vols 4to,  *is  oo 

Freudemacher,  P.  W.    Electrical  Mining  Installations.     (In- 
stallation Manuals  Series.) i2mo,  *i  oo 

Frith,  J.    Alternating  Current  Design 8vo,  *2  oo 

Fritsch,  J.     Manufacture  of  Chemical  Manures.     Trans,  by 

D.  Grant 8vo,  *4  oo 

Frye,  A.  I.    Civil  Engineers'  Pocket-book i2mo,  leather,  *s  oo 

Fuller,  G.  W.     Investigations  into  the  Purification  of  the  Ohio 

River 4to,  *io  oo 

Furnell,  J.     Paints,  Colors,  Oils,  and  Varnishes 8vo,  *i  oo 

Gairdner,  J.  W.  I.    Earthwork 8vo  (In  Press.) 

Gant,  L.  W.     Elements  of  Electric  Traction 8vo,  *2  50 

Garcia,  A.  J.  R.  V.      Spanish-English  Railway  Terms.  . .  .8vo,  *4  50 
Garforth,  W.  E.     Rules  for  Recovering  Coal  Mines  after  Explo- 
sions and  Fires i2mo,  leather,  i  50 

Garrard,  C.  C.    Electric  Switch  and!  Controlling  Gear (In  Press.) 

Gaudard,  J.     Foundations.     (Science  Series  No.  34.) i6mo,  o  50 

Gear,  H.  B.,  and  Williams,  P.  F.     Electric  Central  Station  Dis- 
tributing Systems iimo,  *3  oo 

Geerligs,  H.  C.  P.    Cane  Sugar  and  Its  Manufacture 8vo,  *s  oo 

Geikie,  J.     Structural  and  Field  Geology 8vo,  *4  oo 

Mountains,  Their  Origin,  Growth  and  Decay 8vo,  *4  oo 

The  Antiquity  of  Man  in  Europe 8vo,  *s  oo 

Georgi,  F.,  and  Schubert,  A.    Sheet  Metal  Working.    Trans. 

by  C.  Salter 8vo,  3  oo 

Gerber,  N.     Analysis  of  Milk,  Condensed  Milk,  and  Infants' 

Milk-Food 8vo,  i  25 

Gerhard,  W.  P.     Sanitation,  Water-supply  and  Sewage  Disposal 

of  Country  Houses i2mo,  *2  oo 


D.  VAN  NOSTRAND  COMPANY'S  SHORT-TITLE  CATALOG  15 


Gas  Lighting.     (Science  Series  No.  in.) i6mo,  o  50 

Gerhard,  W.  P.    Household  Wastes.     (Science  Series  No.  97.) 

i6mo,  o  50 

House  Drainage.     (Science  No.  63.) i6mo,  o  50 

Sanitary  Drainage  of  Buildings.     (Science  Series  No.  93.) 

i6mo,  o  50 

Gerhardi,  C.  W.  H.    Electricity  Meters 8vo,  *4  oo 

Geschwind,  L.     Manufacture  of  Alum  and  Sulphates.     Trans. 

by  C.  Salter 8vo,  *s  oo 

Gibbs,  W.  E.    Lighting  by  Acetylene i2mo,  *i  50 

Gibson,  A.  H.     Hydraulics  and  Its  Application 8vo,  *5  oo 

Water  Hammer  in  Hydraulic  Pipe  Lines i2mo,  *2  oo 

Gibson,  A.  H.,  and  Ritchie,  E.  V.    Circular  Arc  Bow  Girder. 4to,  *3  50 

Gilbreth,  F.  B.     Motion  Study.    A  Method  for  Increasing  the 

Efficiency  of  the  Workman i2mo,  *2  oo 

—  Primer  of  Scientific  Management i2mo,  *i  oo 

Gillmore,  Gen.  Q.  A.    Limes,  Hydraulics  Cement  and  Mortars. 

8vo,  4  oo 

Roads,  Streets,  and  Pavements i2mo,  2  oo 

Golding,  H.  A     The  Theta-Phi  Diagram i2mo,  *i  25 

Goldschmidt,  R.    Alternating  Current  Commutator  Motor .  8vo,  *3  oo 

Goodchild,  W.    Precious  Stones.     (Westminster  Series. ).8vo,  *2  oo 

Goodeve,  T.  M.    Textbook  on  the  Steam-engine i2mo,  2  oo 

Gore,  G.    Electrolytic  Separation  of  Metals .8vo,  *3  50 

Gould,  E.  S.    Arithmetic  of  the  Steam-engine i2mo,  i  oo 

Calculus.     (Science  Series  No.  1121) i6mo,  o  50 

High  Masonry  Dams.     (Science  Series  No.  22.) ...  i6mo,  o  50 

Practical  Hydrostatics  and  Hydrostatic  Formulas.     (Science 

Series.) i6mo,  o  50 

Gratacap,  L.  P.    A  Popular  Guide  to  Minerals 8vo,  *3  oo 

Gray,  J.    Electrical  Influence  Machines i2mo,  2  oo 

Gray,  J.     Marine  Boiler  Design  .  .  .' i2mo,  *i  25 

Greenhill,  G.    Dynamics  of  Mechanical  Flight.  Li.  ^t . . .  .8vo,  *2  50 
Greenwood,  E.     Classified  Guide  to  Technical  and  Commercial 

Books 8vo,  *3  oo 

Gregorius,  R.     Mineral  Waxes.    Trans,  by  C.  Salter.  . . i2mo,  *3  oo 

Griffiths,  A.  B.    A  Treatise  on  Manures I2mo,  3  oo 


16    D.  VAN  NOSTRAND  COMPANY'S  SHORT-TITLE  CATALOG 

Griffiths,  A.  B.     Dental  Metallurgy 8vo,  *3  50 

Gross,  E.     Hops 8vo,  *4  50 

Grossman,  J.     Ammonia  and  its  Compounds i2mo,  *i  25 

Groth,  L.  A.     Welding  and  Cutting  Metals  by  Gases  or  Electric- 
ity.    (Westminster  Series.) 8vo,  *2  oo 

Grover,  F.     Modern  Gas  and  Oil  Engines 8vo,  *2  oo 

Gruner,  A.     Power-loom  Weaving 8vo,  *3  oo 

Giildner,    Hugo.      Internal-Combustion    Engines.      Trans,    by 

H.  Diedrichs 4*0,  *io  oo 

Gunther,  C.  0.    Integration i2mo. 

Gurden,  R.  L.    Traverse  Tables folio,  half  mor.,  *7  50 

Guy,  A.  E.  .  Experiments  on  the  Flexure  of  Beams 8vo,  *i  25 

Haenig,  A.    Emery  and  the  Emery  Industry i2mo,  *2  50 

Hainbach,  R.     Pottery  Decoration.     Trans,  by  C.  Slater.  .  12010,  *3  oo 

Hale,  W.  J.     Calculations  of  General  Chemistry i2mo,  *i  oo 

Hall,  C.  H.     Chemistry  of  Paints  and  Paint  Vehicles i2mo,  *2  oo 

Hall,  G.  L.    Elementary  Theory  of  Alternate  Current  Work- 
ing    8vo,  *i  50 

Hall,  R.  H.     Governors  and  Governing  Mechanism i2mo,  *2  oo 

Hall,  W.  S.     Elements  of  the  Differential  and  Integral  Calculus 

8vo,  *2  25 

Descriptive  Geometry 8vo  volume  and  4to  atlas,  *3  50 

Haller,  G.  F.,  and  Cunningham,  E.  T.    The  Tesla  Coil i2mo,  *i  25 

Halsey,  F.  A.     Slide  Valve  Gears 7 i2mo,  i  50 

The  Use  of  the  Slide  Rule.   (Science  Series.) i6mo,  o  50 

Worm  and  Spiral  Gearing.     (Science  Series.) i6mo,  o  50 

Hancock,  H.     Textbook  of  Mechanics  and  Hydrostatics 8vo,  i  50 

Hancock,  W.  C.  Refractory  Materials.  (Metallurgy  Series. (In  Press.) 

Hardy,  E.     Elementary  Principles  of  Graphic  Statics i2mo,  *i  50 

Harrison,  W.  B.     The  Mechanics'  Tool-book i2mo,  i  50 

Hart,  J.  W.     External  Plumbing  Work 8vo,  *3  oo 

Hints  to  Plumbers  on  Joint  Wiping 8vo,  *3  oo 

Principles  of  Hot  Water  Supply: 8vo,  *3  oo 

Sanitary  Plumbing  and  Drainage 8vo,  "3  oo 

Haskins,  C.  H.     The  Galvanometer  and  Its  Uses i6mo,  i  50 

Hatt,  J.  A.  H.    The  Colorist .  Second  Edition.  . .  .square  larno,  *i  50 


D.  VAN  NOSTRAND  COMPANY'S  SHORT-TITLE  CATALOG     17 

Hausbrand,  E.     Drying  by  Means  of  Air  and  Steam.     Trans. 

by  A.  C.  Wright i2mo,     *2  oo 

—  Evaporating,  Condensing  and  Cooling  Apparatus.     Trans. 

by  A.  C.  Wright 8vo,     *5  oo 

Hausmann,   E.     Telegraph   Engineering 8vo,    *3  oo 

Hausner,  A.     Manufacture  of  Preserved  Foods  and  Sweetmeats. 

Trans,  by  A.  Morris  and  H.  Robson 8vo,     *3  oo 

Hawkesworth,  T.     Graphical  Handbook  for  Reinforced  Concrete 

Design 4to,     *2  50 

Hay,  A.     Continuous  Current  Engineering ,8vo,    *2  50 

Hayes,  H.  V.    Public  Utilities,  Their  Cost  New  and  Deprecia- 
tion  8vo,    *2  oo 

Public  Utilities,  Their  Fair  Present  Value  and  Return, 

8vo,    *2  oo 

Heather,  H.  J.  S.    Electrical  Engineering 8vo,     *3  50 

Heaviside,  O.     Electromagnetic  Theory.     Three  volumes. 

8vo,  Vols.  I  and  II,  each,    *s  oo 
Vol.  Ill,    *7  50 

Heck,  R.  C.  H.     Steam  Engine  and  Turbine 8vo,    *3  50 

Steam-Engine  and  Other  Steam  Motors.    Two  Volumes. 

Vol.    I.     Thermodynamics  and  the  Mechanics 8vo,     *3  50 

Vol.  II.     Form,  Construction  and  Working 8vo,     *5  oo 

Notes  on  Elementary  Kinematics 8vo,  boards,     *i  oo 

Graphics  of  Machine  Forces 8vo,  boards,     *i  oo 

Heermann,  P.     Dyers'    Materials.     Trans,   by   A.  C.  Wright. 

I2mo,     *2  50 
Hellot,  Macquer  and  D'Apligny.     Art  of  Dyeing  Wool,  Silk  and 

Cotton 8vo,     *2  oo 

Henrici,  O.     Skeleton  Structures 8vo,       i  50 

Hering,  D.  W.    Essentials  of  Physics  for  College  Students. 

8vo,     *i  75 
Hermann,  G.     The  Graphical  Statics  of  Mechanism.     Trans. 

by  A.  P.  Smith I2mo,       2  oo 

Herring-Shaw,  A.    Domestic  Sanitation  and  Plumbing.  Two 

Parts 8vo,     *5  oo 

Elementary  Science  of  Sanitation  and  Plumbing ....  8vo,     *2  oo 

Herzfeld,  J.     Testing  of  Yarns  and  Textile  Fabrics 8vo,     *3  50 


18     D.  VAN  NOSTRAND  COMPANY'S  SHORT-TITLE  CATALOG 

Hildebrandt,  A.     Airships,  Past  and  Present 8vo,  *3  50 

Hildenbrand,  B.  W.     Gable-Making.      (Science  Series  No.  32.) 

i6mo,  o  05 

Hildich,  H.     Concise  History  of  Chemistry iimo,  *i 

Hill,  J.  W.     The  Purification  of  Public  Water  Supplies.     New  52 

Edition (/n  Press.) 

—  Interpretation  of  Water  Analysis (In  Press.) 

Hill,  M.  J.  M.    The  Theory  of  Proportion 8vo,  *2  50 

Hiroi,  I.     Plate  Girder  Construction.     (Science  Series  No.  95.) 

i6mo,  o  50 

Statically-Indeterminate  Stresses i2mo,  *2  oo 

Hirshfeld,    C.    F.      Engineering     Thermodynamics.     (Science 

Series.) i6mo,  o  50 

Hobart,  H.  M.     Heavy  Electrical  Engineering 8vo,  *4  50 

Design  of  Static  Transformers 8vo,  *2  oo 

Electricity 8vo,  *2  oo 

- —  Electric  Trains 8vo,  *2  50 

Electric  Propulsion  of  Ships 8vo,  *2  oo 

Hobart,  J.  F.    Hard  Soldering,  Soft  Soldering,  and  Brazing . 

I2H10,  *I    OO 

Hobbs,  W.  R.  P.     The  Arithmetic  of  Electrical  Measurements 

1 2 mo,  o  50 

Hoff,  J.  N.     Paint  and  Varnish  Facts  and  Formulas i2mo,  *i  50 

Hole,  W.     The  Distribution  of  Gas 8vo,  *7  50 

Holley,  A.  L.     Railway  Practice folio,  6  oo 

Hopkins,  N.  M.     Experimental  Electrochemistry 8vo, 

Model  Engines  and  Small  Boats i2mo,  i  25 

Hopkinson,  J.,  Shoolbred,  J.  N.,  and  Day,  R.  E.     Dynamic 

Electricity.     (Science  Series  No.  71.) i6mo,  o  50 

Horner,   J.     Practical   Ironfounding 8vo,  *2  oo 

Gear  Cutting,  in  Theory  and  Practice 8vo,  *3  oo 

Houghton,  C.  E.    The  Elements  of  Mechanics  of  Materials.  i2mo,  *2  oo 

Houllevigue,  L.     The  Evolution  of  the  Sciences 8vo,  *2  oo 

Houstoun,  R.  A.     Studies  in  Light  Production i2mo,  *2  oo 

Hovenden,  F.     Practical  Mathematics  for  Young  Engineers, 

i2mo,  *i  oo 

Howe,  G.     Mathematics  for  the  Practical  Man i2mo,  *i  25 


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Hurst,  G.  H.     Handbook  of  the  Theory  of  Color 8vo,  *2  50 

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Jacob,  A.,  and  Gould,  E.  S.     On  the  Designing  and  Construction 

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Jannettaz,  E.     Guide  to  the  Determination  of  Rocks.     Trans. 

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Jehl,  F.     Manufacture  of  Carbons 8vo,  *4  oo 

Tennings,    A.    S.     Commercial   Paints   and   Painting.     (West- 
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Johnson,  J.  H.    Arc  Lamps.     (Installation  Manuals  Series.) 

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Johnson,  W.  McA.     The  Metallurgy  of  Nickel (In  Preparation.) 

Johnston,  J.  F.  W.,  and  Cameron,  C.     Elements  of  Agricultural 

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Joly,  J.     Radioactivity  and  Geology I2mo,  *3  oo 

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Joynson,  F.  H.     Designing  and  Construction  of  Machine  Gear- 
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Jiiptner,  H.  F.  V.     Siderology:  The  Science  of  Iron 8vo,  *5  oo 

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Kemp,  J.  F.     Handbook  of  Rocks 8vo,  *i  50 

Kennedy,   A.   B.   W.,   and   Thurston,   R.   H.     Kinematics  of 

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Kennedy,  A.  B.  W.,  Unwin,  W.  C.,  and  Idell,  F.  E.     Compressed 

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Kent,  W.    Strength  of  Materials.     (Science  Series  No.  41.).  i6mo,  050 

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Larner,  E.  T.    Principles  of  Alternating  Currents i2mo,  *i  25 

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Latimer,  L.  H.,  Field,  C.  J.,  and  Howell,  J.  W.     Incandescent 

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D.  VAN  NOSTRAND  COMPANY'S  SHORT-TITLE  CATALOG     23 

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Le  Doux,  M.     Ice-Making  Machines.     (Science  Series  No.  46.) 

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Lord,  R.  T.     Decorative  and  Fancy  Fabrics 8vo,     *3  5<> 

Loring,  A.  E.     A  Handbook  of  the  Electromagnetic  Telegraph. 

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Low,  D.  A.    Applied  Mechanics   (Elementary) i6mo,      080 

Lubschez,  B.  J.    Perspective i2mo,     *i  50 

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Mansfield,  A.  N.     Electro-magnets.     (Science  Series  N   .  64) 

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Marshall,  W.J.,  and  Sankey,  H.  R.    Gas  Engines.    (Westminster 

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Maxwell,  J.  C.     Matter  and  Motion.     (Science  Series  No.  36.) 

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McCullough,  R.  S.     Mechanical  Theory  of  Heat .  8vo,       3  50 

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McKnight,   J.   D.,  and  Brown,   A.   W.     Marine   Multitubular 

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Mitchell,  C.  F.  and  G.  A.     Building  Construction  and  Draw- 
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Series.) i6mo,  o  50 

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Nesbit,  A.  F.    Electricity  and  Magnetism (In  Preparation.) 

Neuberger,   H.,  and  Noalhat,  H.     Technology  of  Petroleum. 

Trans,  by  J.  G.  Mclntosh. 8vo,  *io  oo 

Newall,  J.  W.  Drawing,  Sizing  and  Cutting  Bevel-gears.  .8vo,  i  50 
Newbiging,  T.  Handbook  for  Gas  Engineers  and  Managers, 

8vo,  *6  50 

Nicol,  G.     Ship  Construction  and  Calculations 8vo,  *4  50 

Nipher,  F.  E.     Theory  of  Magnetic  Measurements i2mo,  i  oo 

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Nolan,  H.     The  Telescope.     (Science  Series  No.  51.) i6mo,  o  50 

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Nugent,  E.    Treatise  on  Optics i2mo,  i  50 

O'Connor,  H.  The  Gas  Engineer's  Pocketbook.  .  .  i2mo,  leather,  3  50 
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Pakes,  W.  C.  C.,  and  Nankivell,  A.  T.    The  Science  of  Hygiene. 

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Robinson,  J.  B.     Architectural  Composition 8vo,  *2  50 

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Rogers,  A.     A  Laboratory  Guide  of  Industrial  Chemistry.  .  i2mo,  *i  50 

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Rogers,  F.     Magnetism  of  Iron  Vessels.     (Science  Series  No.  30.) 

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Rollins,  W.     Notes  on  X-Light 8vo,  5  oo 

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Rose,  J.     The  Pattern-makers'  Assistant 8vo,  2  50 

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Rose,  T.  K.  The  Precious  Metals.  (Westminster  Series.) .  .8vo,  *2  oo 
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Roth.  Physical  Chemistry 8vo,  *2  oo 

Rothery,  G.  C.,  and  Edmonds,  H.  0.  The  Modern  Laundry. 

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Rowan,  F.  J.  Practical  Physics  of  the  Modern  Steam-boiler^Svo,  *3  oo 
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Sanford,  P.  G.     Nitro-explosives 8vo,  *4  oo 

Saunders,  C.  H.     Handbook  of  Practical  Mechanics :''.  i6mo,  i  oo 

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Schidrowitz,  P.    Rubber,  Its  Production  and  Uses 8vo,  *5  oo 

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Schmall,  C.  N.     First  Course  in  Analytic  Geometry,  Plane  and 

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Schumann,  F.     A  Manual  of  Heating  and  Ventilation. 

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Schwartz,  E.  H.  L.     Causal  Geology 8vo,  *2  50 

Schweizer,  V.,  Distillation  of  Resins 8vo,  *3  50 

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Searle,  G.  M.     "  Sumners'  Method."     Condensed  and  Improved. 

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Seaton,  A.  E.    Manual  of  Marine  Engineering 8vo,  8  oo 

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Seidell,  A.    Solubilities  of  Inorganic  and  Organic  Substances .  8vo,  *3  oo 

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Sellew,  W.  H.     Steel  Rails 4to,  *i2  50 

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Senter,  G.    Outlines  of  Physical  Chemistry i2mo,  *i  75 

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Sewell,  T.    The  Construction  of  Dynamos 8vo,  *3  oo 

Sexton,  A.  H.     Fuel  and  Refractory  Materials  .    12010,  *2  50 

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Shaw,  H.  S.  H.     Mechanical  Integrators.    (Science  Series  No. 

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Shunk,  W.  F.     The  Field  Engineer i2mo,  mor.,  2  50 

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Smith,  F.  E.     Handbook  of  General  Instruction  for  Mechanics. 

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Smith,  J.  C.    Manufacture  of  Paint 8vo,  *s  50 

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